I used to play squash several times per week.. When a guy interfered with you getting to the shot, it was a Let, if he interfered with the shot, it was Stroke. Simple. When I play racquetball everything is a Let. Drives me crazy.
Technically, the let and stroke in squash are very similar to a hinder and avoidable hinder in racquetball. The difference I find between the two is that squash players of all levels call stroke way too often and seemingly try to win a game from strokes, while in racquetball, players tend not use the avoidable frequently enough (as you already stated. It is most likely that this is the case in racquetball because of the lack of understanding of the rules and wanting to give the benefit of the doubt while playing a friendly game.
I'm still bitter about my getting trouble from the ref in a squash tournament back in the early 90's because I didn't hold up on an easy shot. Apparently I am supposed to hold up when my opponent is in front of me and hope for the stroke. In racquetball, the onus is on my opponent to get out of the way. That is why you see a lot of jumping.
I love squash.
If a player stands in front of your shot and gets whacked by the ball.. it's self inflicted.
If a player stands too close to your swing and gets whacked by your racquet, it's self inflicted.
If a player bleeds on the court, he loses.
The ref was wrong. Your opponent was attempting a self inflicted ball whacking.
I like how you think Daniel.