StrateandLevel:
>> The CAA have no idea how many of the licensed pilots work as pilots or even how many have valid ratings. All their statistics can tell you is how many have valid medicals. <<
Complete and utter bollocks. Do you have a Class 1? If so, the form the doc got you to fill out before the exam asked, amongst other things, type of flying you do, type of aircraft, and hours since last medical. These will easily give the stats that were referred to (in the UK).
Everybody else: It's simple.
Hours=experience=less of a training risk.
Many people get through the IR issue then fail the renewal.
Many people pass the IR, get a job and fail the sim course (for a variety of reasons). Still more pass the sim course but fail the line training.
The IR is a (very) basic qualification. Almost everything you do in airline training will be more demanding.
Light aircraft experience is of little benefit when it comes to the demands of airline training. The oft-quoted 1000 hours is an arbitrary figure, but one that experience has shown to be a good baseline.
As is often the case, the process may not SEEM fair to you, but it does generate an essentially level playing field once the minimum requirements are met.
We hire all sorts of people, 509-ers, self-improvers, older people, the whole range. Without a doubt, the ones with more general flying experience have the most success.