[thousandwords]

Yes I have experienced this as well.
I believe you are correct- the message basically is saying that the car automatically takes the Emergency Parking Brake off when you shift out of park as per your settings.
My guess (and it is just a guess) is that it is just a reminder and as such, as you call it, "a harmless nuisance". I could be wrong though, and if you find out otherwise I would really appreciate it if you would share with the rest of us here so that appropriate remedial steps could be taken.

 

[thousandwords]

I thought maybe, it is just the EPB system booting up after say a night of cold. I did do an experiment, usually I wait until the dasboard display is done doing its graphics and shows the 0MPH before I put it in gear. In my test, I did not wait and put the car in gear a split second after I started the car. I got the EPB message for longer with beeping. The same beeping you would get if you activated or deactivated the feature.

That's the only scenario I got the message during- hurrying up to shift a split moment after starting. Bad habit to start with without any funky messages. Once I noticed the pattern I told myself I should wait a few seconds each time I get going, but once in a while I find myself just shifting and that EBP message usually pops up.

 

[thousandwords]

I believe EPB represents Electronic/Electric Parking Brake.
Not Emergency Parking Brake.

I stand corrected, thanks for pointing that out.

Yet just because the can of worms was open, please indulge me a few minutes of rambling as a justification of sorts and an exercise in imagination.
Hopefully this will not be completely out of line.
If it is, my apologies.

I am using the "Emergency" alternative for a reason though- that's what automatically comes to mind when I see the "E" in the EPB.
Because the most important function of that brake is as an emergency brake.
Yes it is a parking brake as well, but first and foremost it's an emergency brake.
Just like with the old school cable actuated "hand brake" of yore, all the way back to manual transmissions.
Yes back then people used to pull the hand/parking brake up after stopping before leaving the car so that it won't start rolling downhill but in fact most people left their stick cars in first gear for that purpose too.
The hand brake (and the fact it was not hydraulic) justified it's existence mostly because back up brake (of a different nature than hydraulic as the regular brake) was a matter of life and death in case of catastrophic primary brake failure, be it brake fade in heavy use (and in the beginning brake fluids boiled faster than say our DOT 5.1) or leaky hydraulic lines.
Engine fails- you end up stranded. Same with clutch, transmission etc.
Brake fails you might easily die.
If there is ONE single component of a vehicle you HAVE to choose for a back up system it's the brakes.
And it was not uncommon either. Long descents in hot summer days while on vacation in the Alps, fluid reaching boiling point, you lose braking effectiveness- not a problem, pull the hand brake and day is saved. You wait on the shoulder for a while till temp lower to safe levels then you are back on your way to that hotel and you'll make sure you will stop from time to time so you won't fade your brakes again.
When hand brake morphed from mechanical/cable to electric motor, it was probably just natural to call it Electric Parking Brake, or EPB for short, obviously
Except you triggered people like me who saw the emergency nature of the brake as the justification ha ha because it's main role still did not change much.
Yes you cannot leave automatic transmission cars "in gear" while stopped so they won't roll, but you have a parking pawl for that, albeit it's not the brightest idea to trust a ton worth of metal with that little piece.
But just as before, you need to have a back up in case you need to stop in an emergency and brake pedal is not working on you.
That's the reason that step motor follows the piston as the pads wear out. So that if you need to brake in a split second the brake is right against the piston and engages almost instantly.
If that brake was primarily a parking brake it won't matter it took a few seconds to engage. So you could design it so that each time you disengage it, it retracts all the way in, then upon engaging it it travels until it meets the piston.
But back to the Alps vacation scenario, imagine pedal brake fading, with you quickly approaching that tight switchback right in front of you, with the side of the mountain dropping a mile down the chasm.
But no sweat- you confidently remember you have a "back-up" electric brake, which you promptly engage by pulling the little button up.
Only to hear the seemingly never ending sound of the electrical motor unwinding all the way to the piston.
Which it finally reached- just as you were becoming airborne.
And your last thoughts as the Gs become negative are "if only the electric motor was just ONE second faster..."

Anyways, by now you could all understand why my handle is "thousandwords" ha ha ha.

In truth though, today I am particularly verbose: a few hours ago I visited both the Registry of Motor Vehicles and my insurance- with the title and the Bill of sale I received from Toyota yesterday.
Yup, I made it known to the wider world- she's mine.
As childish as this sounds, it just made me feel so happy. I even stopped by at a car wash for a nice scrub and a fresh coat of wax. Ha ha ha.
Came home, had a hearty meal and a glass of red wine.
Then checked the RAV4 forums.
Lo and behold- somebody pointed out a fallacy regarding an acronym I regrettably misunderstood.
Point gladly taken!
But then again, people of a thousand words sometimes do tend to go tangents.
Especially when elated.

Happy New Year everybody!

 

[thousandwords]

In no way is the EPB in the RAV4 an "emergency" brake. In the classic emergency brake you cite, you can gradually activate it, thus slowing down your car in an "emergency". Can't do that with the EPB; it is basically either off (wheels turning) or on (wheels locked). Yes, there is a short activation time, but still there is really no in between where you can slow down the car in an emergency.

The dual reservoir brake system was put in cars over 50 years ago in case of a brake system leak/failure which works well for most "emergencies". The latest developments in traction control, anti-lock brake systems, and stability control, make the modern braking system very reliable.

True, never thought of the on/off nature of the electric brake, and it's a fair point actually. I do wander though, just a hypothetical, let's say you do your own brakes (I actually do mine these days, just did the fronts and the first rear rotor is coming today) and you do not hang the caliper from bungee cord. It even has the carrier on it while you swap rotor. All that weight pulls on the brake line, which as a result develops a minute leak. I know it is a stretch but for the sake of argument. So in time your fluid level drops slowly, you never check reservoir level, at some point it goes below minimum and now you have air in the lines. One day you need to go on a steep downhill and brake pedal is mushy, barely slows you down.
My question is this: what would happen if you activate the EPB? It would engage fully instantly as you pointed out. Is it a bad idea to do it?
Asking this because your point is really valid here.