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.
I had no idea. Hackaday explains as well as some other things I’d not though about.
https://hackaday.com/2017/08/17/living-on-mars-the-stuff-you...