I agree- we do work flatwork with our dogs prior to them ever being asked to jump. Sure, there are probably still plenty who don't, but a large amount of the agility community here in the US has caught up in that regard and has learned the value of teaching on the flat first. My five month old is learning recall to heels, backsides, threadles, pushes, forward and lateral sends, tight turns (cik and cap), and front, blind, and rear crosses all on the flat now. It is all just a really fun game for her right now. She will have all of the skills before she is even a year old without ever having been asked to take a jump. It is what is taught around here by the better trainers now.
However, it doesn't prevent ETS from developing if there is an eye issue. You can be regarded as one of the best handlers out there who did all of the right things and still wind up with an ETS dog. I think a talented trainer/handler can teach a dog all of the flatwork, and to jump with confidence, and avoid/fix some of the other reasons dogs might start taking off early, but in the ones it is truly a vision issue, there isn't a whole lot that can be done. I do know that in certain lines it really is a vision issue. Regardless of the area, training method, trainer/handler, the ones with true vision issues are going to have trouble jumping.
There is someone I know who has a dog from a particular line known for ETS. The bitch has ETS. She had an oops litter, and both puppies also wound up with ETS. They are not both owned by the same person or trained the same way. I know one is a fabulous handler who didn't create it.
What I'm getting at is that it isn't just that we are behind the times here in the US. There are many potential causes of ETS, and vision and certain structural faults can cause it. In those cases, the blame unfortunately is the dog, not where the handler has messed up.