Bot Paths Bots can move off fences but not B

This behavior has nothing to do with the fence blocks. If you put stone blocks, the bots would act the same way. B can't step onto a stair that way, but R/L can.

The dimensions of a fence block is the same as a stone or dirt block (apparently a motor is also the same dimensions). You can see the actual dimensions of the various blocks here: https://mekoramaforum.com/threads/physical-dimensions-of-mekorama-blocks.635/

 

Just the rules of the game. If you turn the stairs around, B can walk down. If you lift the stairs up one block, B can go up. If you turn the stairs sideways, no bots can step onto them (but R/L can step off a stair sideways, while B can't). The differences in behavior allow builders to make different paths that require using different bots.