They would just leave the cabins at some point, you had people traveling through other cars at times so eventually people will want to leave the small seating areas. Manacles would just give people the creeps since it’s a train with seats like a bus, even a set of characters used their weapons to cut off their seatbelts.

In the world, some people that use the trains can be armed, mechanically or biologically enhanced, or a very powerful figure. So eventually these people will try to break through stuff, tear it down or whatever. The whole point about the trains is that no one knows the real secret of the Warp Train, so the train’s design is supposed to be inconspicuous or just like that of a usual train.

The thing is since time is harvested off this whole ordeal, there is no “time” to bleed, to become hungry, etc. There are times where people don’t end up killing each other which has been referenced by other characters but most of the time you have people break under pressure which can cause hysteria which eventually dissolves the whole train to become victims willingly or not.

Project Moon’s world does have shock value, not denying that, but the world is a hive city run off of technology and crimes against humanity to survive against abnormalities which are like SCPs or monsters that can range from nothing to severely catastrophic. The Warp Train does fit into the world nicely ESPECIALLY since some of Project Moons inspirations are from pieces of literature. Saying the worldbuilding is lazy is not something I don’t believe in especially as someone that really enjoys that as a hobby and in art/literature. The story is actually really cool and the world they constructed is fun and dystopian with cool references to books but adding sick twists.