It's a good point. I also have to (far to often for me) write Rams involving some of the points you have mentioned. For me there are a few issues compounding the problem. Firstly a lot of sites see the injury waiver as a reason not to have a full grasp on potential risks. Most sites around the uk don't run as stand alone businesses, by which I mean the owner/organiser has another job as Airsoft dosnt have the mainstream appeal or the high turnover of paintball. Thirdly there is a certain level of risk which goes along with paying toy guns in a remote area of the woods, as with any outdoor activity, which we must except.
It isn't something I have ever thought about as 90% of my games a cqb where the same zone is in the same building or within a minute or two.
Airsoft/paintball sites seem to me not to dance to the same h+s music that the rest of the business world is adopting. Is this because the hse don't regulate pastimes? I don't know. And at the end of the day we all get shot at for fun! Explain that one to a "normal" person.