OK this is the way I remember it.
When I started flying, in about 1986 I think, I thought we were allowed to go to 500 ft and there was no restriction on crossing roads 500 ft was a bit low but that was a bit rubbery, whats a few hundred ft between friends? but it really was not that bad in those type of planes. Then we could go to 5000 ft and all was pretty OK and most of the ultralighters were happy with that and we had no real problems like we have now.
Then we started to get ex GA pilots who no longer could pass their medicals these guys generally were not happy with what we had and wanted to go higher faster and heavier, as they would being ex GA. Still things were fairly OK up to about 2006 but we were getting more and more GA like aircraft, Sting, Sabre, Lightwing Speed, Spitfire, Lightning and numerous others.
Since then there has been problems, the Sting crash, Lightwing in the drink near Sydney, the infamous Ferris wheel incident and so on with the threat of litigation. We have had C 150s, Piper Colts and V8 Spitfires inappropriately registered as ultralights. I have given up worrying about it all but I see little point in pretending these things have not happened and the AUF was not hi-jacked.