It probably doesn't hurt for "basic safety instructions" to be permenantly posted somewhere (it may be already, I really don't know), however with that being said the real responsibility should lie on the cacher themselves. Geocaching is really no different than hiking (or rock climbing, scuba diving, etc). There's safety information out there if you want to look for it (prior to doing it), and if you don't act responsible and look, hey that's your own fault.
I, personally, carry a compass with me. I've only had to use it once. I see no valid argument to not carry one, due to how light and small they are. In addition to the compass, I always have a flashlight, extra batteries, something to drink, etc. Nothing difficult to carry, it just makes sense (no web page had to tell me this) that "things happen" and "be prepared". Marking a waypoint where you park is an invaluable tool. But more than that, looking over a map of where you're going to be and work out a "safety bearing" that you can use with a compass to get out of where you are.
An example... I decided one night that it'd be a great idea to finally do a night cache. The place was somewhat marshy, away from the city (so very very dark). I knew beforehand that there was alot of tree cover so I knew it was likely the gps would lose signal occasionally. I looked over an aerial map, saw that if I went northeast from any spot I'd eventually hit a road within a couple miles. I also marked a waypoint where I parked. All went well for the most part until we were working our way out and we lost the gps signal and it didn't appear that it was coming back. I felt that I should head in a specific direction, but out came the compass, found northeast and headed off towards the road. This ended up taking us through some really nasty areas, knee deep in marshy water, I definately wasn't a happy camper. At any rate, the compass helped, and to be honest this was a cache I should've waited to do. Wasn't gc.com's fault I went at it gungho, and wasn't the cache owners fault. I did log it tho, and it felt great Doing a cache like this without a compass is incredibly stupid.
My point is, one should know what they're getting into before they do it. They should be prepared and it's the cachers responsibility to be prepared.
And another thing... Almost everyone has the ability to put up a web page these days. If the OP is so worried about the lack of safety information, put up a web page documenting what you think others should know. I'm sure there are alot of people who would appreciate the effort and it would be yet another asset to the community.