I think you are being a bit unfair Rob. Everybody knows caves have nice flat and even floors. I've seen loads like that on television or in films so it must be true.
Absolutely, mines are way too dangerous for robots.
When walking in mines you can't see for all the giant spider webs, then inevitably you fall through the floor into an old mine cart which starts rolling down a track at speed, as it gets fast it will hit points in the track and veer off crashing through a very flimsy balsa wood barricade that takes you onto a kind of huge wooden roller coaster ride in a massive chamber half full of lava, before eventually you hit the end and are catapulted through the air to land back at your colleagues feet. It has happened to me just so, on more occasions than I care to remember - the films are accurate.
I think robots can't cope with that sort of carry on, keep them in caves.