I'm surprised you have only come across two other people - good basic obedience (including recall) under severe temptation is the foundation of gundog work.

Having a well trained dog is hard work - you get out what you put in, and I never separate training mode from having a ramble. Some dogs are easier than others, some owners/trainers have a natural authority that dogs pick up on, experience helps because you know how to avoid teaching them bad habits, but it still take a lot of work, and to be fair, more than the average pet owner is willing to put in, but you cannot have a well trained dog without it.

While they can appear to improve with age, it is not that their training is any better, more likely that as they get older, the distractions hold less appeal than they would to the average puppy/young dog that is excited about life. They are more likely to plod along having a sniff here and there, having a quick hello if they meet another dog, but without the same zest for life these youngsters have. If the distraction is sufficient, then they will still ignore the command.

I think most owners are probably happy to muddle along with a half trained dog, and that's fine if they are happy with that, but they cannot expect a well trained one without putting the time in. I think the biggest problem is that most people don't realise just how much work it does take. Dogs have very poor powers or generalisation. Teaching a dog some basic commands is just the very beginning. Proofing those commands against distractions is a far greater challenge, but is often overlooked.

PS... I struggle too sometimes - it doesn't just happen