Totally similar here in the UK in most Chinese systems, although there will always be at least 'one' decent western student originating from within this Chinese community. But again, none of us should be judged by our Sifus behaviour or commercial teaching, but it has happened and will continue to happen.
In the UK our old NVQ training has recently been replaced and offers Levels 1-6 and I totally see what you're saying about keeping up with these young mofos!
Personally for me, experience in the hall actually teaching/coaching is a must for any wannabe instructor but some do tend to 'teach for the first time' when they open their own schools. I don't think that should be accepted as the 'norm' for Wing Chun people. You should look for a teacher that can offer you some sort of apprenticeship, so you can be assessed 'while' you're helping your teacher to teach!
Only my personal view, but one which influenced my mind tpo start this thread in the first place.
Now I've been teaching for 7 years independently (kind of!) and my own Sifu is interested to see me more these days and catch up. Assessing where he thinks I'm at and advising on what I can do to develop even further.
I only wish I had taken the time more seriously (business wise) as I have only had a handfull of students due to my growing family and work committments.
Hence, why my Flystudio promotions will only ever be minimal until a new team/troupe is developed.