The Deere has a "park" built into the tranny. Won't start without being there, so it STOPS in park too.
Massey is gear too, but will roll if there's a 1/4" incline. Never seen any tractor roll so easy. It gets brakes locked, in gear, and some thought given to where it's parked. (No hills, no new car in front of it)
Little Deere (lawn mower) is hydrostat, and is almost impossible to move without engine running. No need for brakes OR park.
All three get parked in a shed with a LOCKING door. Kids will do things to tractors that adults don't expect. I don't like that sort of suprise.