Here's my thoughts on it.
The problem is that aviiation is, at least to begin with, something that most people get into out of a love for flying. The ultimate, "I can make what I love, what I do".
As such there are always many many applicants for every job and to make matters worse the intstructors job is used by many as a way to build hours for "free" so that they can apply for a better paying career level job with an airline etc.
As such the economics are stacked in favour of the employer because;
1. There are many more wannabe's than jobs
2. Many of those see the pay as substantially topped up by the free hours for which otherwise they would have to pay a hundred ish pounds an hour for. So th next genration of pilots pass CPL on minimum hours get an instructors rating and teach the next batch etc etc.
The unitended consequence of course is that our next generation of pilots get trained by some of the least experienced and I can't help wondering how much accident rates for low hours pilots would come down if the new were taught by the old, as it were.
Of course we could change this by paying more for our flying, but most training PPL's look for the lowest rate possible, which of course misses the point on many levels. This is exactly what I did many years ago and of course you don't know why or by how much you miss the point till later!
Personally I think flight training is some of the best value "buys" in the world. By the truly great bargain is to go to somewhere like Ultimate High at Kemble (for fixed wing) or old leon Smith at Wycombe and get the benefit of huge ammounts of experience and talent for a hardly noticable increase from the lowest common denominator.
My 2 pence worth, go for an "expert shop" (I have no affiliation with those mentioned, other than being a very happy customer) and rejoyce in the value offered (unless of course you are a flight instructor!).