The author has not taken into account that the rear needs to
house the rear wheels, engine, fuel/Adblue tanks.
It will be very costly to and almost impossible to have a
completely flat rear area with a stepless rear door.
Both LE and LF buses each have their pros and cons. Just live
with it since efforts have been put in for stepless buses to begin
with.
However I feel that the Volvo B9TL LF buses are the best
designed LF buses, full LF yet not so narrow rear aisle. Double
deckers seems to be better in terms of flat floor and low/no entry
designs. It will be good for more LF double deckers.