I have this issue as well. 2013 RAV4 XLE. It is a valid issue, as this is the first time with any of my Toyotas that I have perceived the number of miles traveled and the 'range' miles do not equal the rated size of the tank. I have owned several Toyotas since 1986. This is the first time the numbers don't add up to reflect the rated size of the tank.
We do not need a hidden reserve that can never be used. Is it a 15.9 gallon tank? Then let us decide how to use the 15.9 gallons, including being able to see it and access it.
In my case, the addition of the traveled miles and the range miles equals 360 miles. At 27 mpg that reflects only a 13.3 gallon tank. This is digital information in a computer age. It's accurate. Toyota--There is a problem, so let's stop rationalizing it away. Wonderful vehicle(s), but this fuel tank issue is at least very inconvenient. We spend too much time having to stop at the gas station.