I have used them since the 1970s, and I think I still have a couple from that time period, lol! But back then, there was no such thing as heat tape or UTH. We had to come up with our own ways of making do.
I think the new human pads have a timer that shuts them off after a while. I am using a couple of really old ones right now for my baby Amazons set up in the bathroom and another one for my baby leopard rats that I am isolating in another room. So although I still use them now and then when I have to set up a snake or two in an odd place (quarantine or some other area I don't usually keep snakes in), I think you would be better off buying products made for your intended use. I think there could be a remote possibility of a fire hazard if they are used improperly, so check with somebody who knows electricity if you are going to use it in an unusual way such as putting weight on it, getting it wet, not having any, or much, air space between the pad and the cage, etc.