CBR was the first mod that was built in WDW.
It opened in the late 1980's and the none of the buildings were more than 2 stories tall.
I guess WDW was trying to save money and did NOT put elevators in as a cost saving measure..
The AB buildings in POR are also two stories tall and do NOT have elevators.
The values were built more recent;y.The All Stars have 3 stories and Pop has 4 stories. All of the buildings at the values have 2 elevators for each building.