It depends on the chips. If you get a chip drop or something similar then yes, they can get bumblefoot from those. If you use composted mulch then it was never an issue for me, but that can end up being expensive.Hurt like splinters and such from wood chips? Darn, I thought wood chips would be an awesome thing for chickens to peck around in. We can usually get them for free, too.
Caliche isn't always in one thick slab layer, like a house foundation. It can concentrate into large lumps. Easy for squirrels to burrow around. We will free feed our hens and we don't want to feed the squirrel population, too. They're a huge problem here. I suspect they've tunneled under the house, too, but that's for the homeowner to deal with.