hello99-wow, that’s quite a approval!
aries: very simple, if the community minhag is NOT to pay, then there is (i believe) no obligaton to pay and that is perfectly in line with everything the shulchan aruch says. I would just make sure that one is 100% sure that such is the community minhag. You might do well to double check with a prominent posek in that community. This is the same as if a community had a widespread custom that plumbers/tutors etc do work for free. If that is the reality, that is the halahca. And unless the service provider clearly stated otherwise at the onset, the beneficiary would not be obligated to pay anything.
If there is a community that has the widespread custom to give $1 then that is the halachic obligation.
HOWEVER if a community has a widespread custom to give shadchanus, then one can NOT obsolve their halachic obligation by giving a token $1 and claim, i “gave” shadchanus. Just the same as one who hires a plumber where the going rate is 150 for a house call, they can’t say here’s a dollar, i’ve fullfulled my obligation to pay. They must research and see what the “going rate or range is, and compensate in such a fashion.