It's not physically more hostile than the moon, but we've never colonized the moon for the same reason. It's really hard to live there for not much benefit. There are plenty of sparsely-inhabited deserts on Earth that are much nicer places to live.
Yes. It will be true for any planetary body that does not have a magnetosphere. But Venus has a magnetosphere. So you can do the old "stick a fucking metal rod into the ground" trick as long as your metal rod doesn't melt... because Venus.
Mars does not have a magnetosphere. The core on Mars stopped spinning so there is no longer the electric dynamo and thus there isn't a potential. So everything has to be a floating potential. That isn't to say that you can't make reference grounds, but it is much more convoluted than "sticking a fucking metal rod into the ground".
Actually if you pay attention to HI-SEAS[0] this has been a cause of an accident (since they replicate Mars habitat.
This problem also, obviously, applies to any planetary body which does not have a magnetosphere. So you don't have magnetic north and you don't have a safe potential ground.