[Flanderian]

This is common. The collar is too high. If your shoulders are more squared than sloping this will often happen. I believe it used to be properly fixed by removing the collar, cutting away excess material and reattaching it. I've also noticed that if a jacket is too snug, or oddly, too loose, these folds can tend to appear.

 

[Flanderian]

If you really want to avoid this problem then you need to go bespoke. Your tailor will crooken the balance of the coat with the neck point being placed a little more backwards on your pattern. You most like have a very erect stance.

The chances are there are other balance related issues with any RTW coat you try on too.

Not to be disputatious, but a decent MTM program shouldn't have a problem dealing with it either. I've had a similar issue most of my life with most RTW patterns, and MTM I've used typically were accustomed to this modification as it's common. In my youth, a decent retail tailor wasn't too bothered by the alteration either, but I fear the general level of skill is now much lower.