Alfaman,
With respect, your direction to the directions for UK charity flights is almost exactly what I am talking about.
In principle, the gaining of a PPL license, or here a PPL, a Recreational Permit or, for instance, an Ultralight license in the USA, grants the owner the right to carry some/a passenger. I am sure most of us know pilots who are steady and reliable hands when they get their license but I'm sure some of us know pilot's who have plenty of hours we wouldn't trust with our lives. The directions lay out the paperwork (and I do not denigrate paperwork,) required and suggested. It does not even suggest that waivers be in writing.
A while ago I was invited to an event where flights were being offered to kids belonging to an organisation that fostered youth interest in aviation. Being a low time mature pilot I declined. Later I read that they had given a record number of flights that day. One of the pilots was quoted as saying that he was happy he got his license three months previously as he had always wanted to give flights at one of those events. This not in a Colt or C150 but in something a good deal more demanding.
I have no idea whether the parents who signed the waiver allowing the kids to fly that day were advised that their kid might be flying with a pilot who had 60 hours total. We have signed waivers for our kids to go on camps and in hindsight we knew very little of the activities and supervision so I won't blast the parents. Life and growing up are not risk free anyway, but I would not want to be the organiser who had to say, "Well, he was qualified . . . ."
Our kids all got 30 min Flight School flights when they were 13 or 14. When we took the two eldest boys they did not both go up at the same time. (Could not do that to MrsVJ) They are both helicopter pilots now! RCAF put them in the same squadron and they even flew together. (I did not think they'd do that.) Now one of them is civilian I worry a little less..