Currently experiencing the Training to Prelim jump.
Novice and BN, you can make mistakes and still get around, many riders love that. Plus when it’s a hobby with a full time job, it’s easier to pop around and have fun at the lower levels and not feel the pressure of being fit enough to get around. The bigger the jumps, the faster the speed, the more demand of work in dressage, not everyone has time to put the work in to be able to aim for those higher levels.
I think most stick to N and BN, some will try to dabble in training, but usually not for long or not as much. Prelim, in Canada, either you want to go somewhere and be an UL rider or your horse can do it. I find the UL’s lack in Canada. People are happier and feel safer with the smaller jumps, the slower speed, the less technical questions and less demanding fitness. Most at the lower levels are doing it for fun and just want to enjoy it.
I found going from PT(BN) to Training was hard, but then I attempted Prelim last year after being at Training level for 5 years (because we had lots of holes, and they were never fixed) and found Prelim to make me poop my pants. I remember sitting in the start box and totally opting to call it a day because I wanted to barf. Made it around and it was the most thrilling experience, but the questions were tougher, the straightness was demanded and the jumps were huge. But the dressage was fun, with more happening and more movements and more technical things it’s definitely more asked of horse and rider, but definitely more fun.
I would say that Prelim is the point where you need to know wtf you’re doing. The holes in your training show, with easier run outs, rails, crappy dressage tests because you’re not forward and fluid. Everything is asked more of rider and horse, and either you’ve got it, or you need to learn it.