Trolling the "gaps"
Remember that the piers are put there for navigation and not for fishing. Fishing is a secondary use of the piers.
Personally I won't fish the gaps anymore because it's not worth the headache to catch fish that don't have any fight left in them.
Bottom line, where there are fish...there will be fishermen - boats or piers. This can be a great time of year to catch large fish near the harbor - it can also be enjoyable, safe, and a quick way to fish.
This comes up every year in early September...the do's and don'ts of harbor fishing. Speaking from many years of experience, the charter boats are the most well behaved of the bunch. I'll also add in, how safe is it really for a pier fishermen to be throwing a 3/4 spoon across a waterway in the dark/fog? To me, that is super dangerous.
Some of my favorite fishing happens this time of year, you can try and pop some monsters early in the morning while the harbor bite lasts, then you can blast out into the lake for a chance at food/numbers.
I know for example, my dad LOVES to fish these harbor fish. Why? I have no idea. But, for the chance to fish with my Dad, I'll jump on it.
Captains want to catch fish (whether they are in a 30 foot boat or a 14 foot dingy; and whether they are getting paid for it or not). Simply put, if you don't like the way someone is fishing......move. Sorry if I'm being a jerk.
EDIT: Not all charter boat captains yell at other anglers either, seems like you've just lumped everybody into one category here.