The "safety" system I have found to be the most dangerous is having to put a HST tractor in neutral to start it. I have only encountered this stupid safety on Deere tractors.
I have a John Deere 3320 (also true for the 3520, and 3720) with a hydrostatic transmission. It does not have to be in neutral to start. So your statement is not accurate for all HST John Deere tractors.