I've been that guy you're talking about - here's my perspective. I'm going down the shore line, pitching at shoreline cover. Trolling motor is down, depth finder is on, I'm looking at that and also looking for stumps and stuff immediately in front of me so I don't smack into them. For the most part, I'm just looking at shore line cover, where am I going to pitch at next, other than that I'm chilling, not really looking at anything. Then, all of a sudden, darn, there's somebody fishing from the bank. Didn't see them - sorry, pitch was already in motion before I noticed you. Sorry - unfortunate side effect of being focused on your fishing. I'm not going out of my way to be a jerk, but I'm not looking all around to check everything out prior to every case either.
I don't know what I'd say to the shore bound angler other than - oops, sorry. If the shore angler really wanted to be noticed, he'd have on hip boots and be out from the bank a couple of feet or so, make an effort to be easier to see and get better casting angles as well. No need to throw a rock or anything over a simple lapse in concentration. Don't be a hater just because I got a boat and you don't. If you are fishing public waters, sooner or later lines are going to get crossed - just chill.
Maybe go the extra mile and find more private waters where you can bank fish and not run into jerks like me, I don't know.
I do know that when I launch my boat on public waters, I don't own the water, I'm just using it. I know that the same thing applies for a bank fisherman. Just because there are mobility issues doesn't mean that he "owns" the particular spaces he's fishing. I really hope that somewhere there is a happy medium here, Bank fishermen don't need to be bouncing lures off of boats or boaters when they get too close. Basically that is assault and that ain't good.
Why don't you just chill and we will all try to get along. My point here is that what you might think is inconsiderate, might just be a case of a guy spacing out a little bit while he's fishing.