Commentary by memnarch (who has not seen the movie)
Space train!
Magnetic boots would still make sense even if the guards had always stayed inside. Sure, training can eventually make it so that worrying about falling over with the turns wouldn’t be a thing, but with boots like that and a metal interior floor, falling would be one less thing of concern.
I personally wouldn’t trust an outdoor environment to stay precisely engineered. What about frost and ice growth? Or even snowfall? There’d need to be a ton of upkeep just to make sure all the rails stay clear of just the weather!
Transcript
Beckett: How do the guards not fall off?
[SFX]: rumble rumble...
[SFX]: Pow! Pow!
Jim: Uh... They had magnetic boots. <scribble>
[SFX]: Pow! Pow!
[SFX]: rumble rumble...
[SFX]: gzzt gzzt gzzt
[SFX]: k-chunk!
Beckett: They seem awfully well prepared.
Jim: Nah. It was the fashion at the time.
Jim: But Chewie was in danger of being smeared against the rock!
[SFX]: rumble rumble...
Chewbacca: They couldn’t build the train with a bit more clearance from the cliff?
Jim: A couple of millimetres is all that’s needed. It’s precision space engineering.
Chewbacca: On a train?
Jim: A space train.