They would have to be careful, it would be them in hot water if they are hiring these without making their customers aware of the legal requirements and the standing regulations, giving the benefit of the doubt I assume they would be. However if not they would be exposing themselves to the actions of whoever hires it, whatever their experience. Reckon they would have a pretty comprehensive disclaimer in the rental agreement.
Come to think about, that may not be stricty true since they can be sold without such information, whatever...Its disaster on hire...just hope nobody flies one into their kids face or such like.
I guess I must be really dumb that I couldn't master a quad in a 'couple of hours' though