Bus = Beechcraft 1900 --> you're on your own, no attendants, just the driver(s)
On a train, you can get up out of your seat whenever you want. It's illegal for me to get out of my seat on a plane while on the ground, unless we're sitting there long enough, in which case, please direct me to the cafe section of the airplane so I can buy a drink.
Oh, and the "cafe section" can't be the galley. I can walk into the cafe car on a train whenver I want, as many times as I want, without getting arrested after being told "sir please return to your seat NOW".
I have no problem with the flight attendants keeping passengers out of the galley. That's your space, not mine. But that means if I'm thirsty, I'm going to ring the flight attendant call button and you are going to get me some water.