GPS Rest Stop

Driving to Akron over the holidays with three girls can require several rest stop breaks. My girls have learned my saying "hold it until it hurts" :) Consequently they announce with plenty of lead time for me to determine where to stop. Which leads me to a mystery - why doesn't the GPS system show rest stops?

It show traffic snarls, and all points of interest - so why isn't a state government highway rest stop listed on the GPS system? How could this be a design feature overlooked. My first thought - it must just be a user operational lack of knowledge - a simple menu choice. But alas - I couldn't easily find it.

This is an irritation - especially when I exit only to discover that a rest stop was only three miles up the highway.