"The vehicle, valued at $689,000, was not paid for by the town or tax dollars. It was acquired through the Federal 1033 program run by the US Department of Defense's Law Enforcement Support Office.
The program transfers weapons, equipment and vehicles from the military to civilian law enforcement agencies."
oh...ok
...why?
Yep, Buses use start buttons to engage the engines, for the longest time, they utilized air starters for their reliability. Though electric starters have become more dependable and robust in the last few decades.
The only hard part now is patience, give it 45 or so seconds for the system to build air so you can actually use the brakes properly. Then disengage the parking brake (pressing the yellow diamond down)
Edit: some buses do not have a parking gear. To "park" some buses you put it in neutral then pull the parking brake tab up.
Boomers: "Kids these days can't drive manual!"
GenX/Y/Z/A: Pops parking brake and shifts into gear
Boomers: Ah well, nevertheless!