A drifter is okay in my opinion as they are really only a danger to themselves - and that's okay as they are aware of the risks.
I hated when I finally got to my fishing hole and the rafters or kayaks or pontooners came dowe. They just go right over your hole they don't care. I just smile, shake my head and mutter obscenities in my head - even give them a friendly wave. Even though I know that often moves the fish enough to get them into the biting mood but still, I have hard feelings when they go by. I know it's tough beans to me and that I have to share my river but I've been able to cope with this by me avoiding going to the river.
Sorry to hear about that. When I drift rivers, I'm on the opposite side of the river from the Angler and try to disturb the water as little as possible.
I think part of the problem is, most are going down by the seat of their pants. They're probably in survival mode and have none to very little river reading skills, so it might not be intentional, but it is the Wack so who knows.
I've heard two people have flipped their boats on the lower Chilliwack this year, one was a guided trip. That scary, because if you know what you're doing there's NO WAY you should be flipping on the lower section!
Other than the Fraser, I don't think jet boats and similar boats should be allowed on rivers. If they are, they should only travel downstream only so they can see other user. I've seen some close calls on the Thompson with kayakers and seadoo's and jet-boaters. It only a matter of time before there's a fatality.