Fair enough, but what do we do when the banks abuse this system to just cut off honest people they just don't want to serve because of whatever reason, maybe profit? That's the definition of discrimiantion.

Banks are required to provide fairly detailed information when refusing basic PAD accounts on those grounds. This doesn't apply to regular bank accounts, but these are specifically the accounts intended by regulators for people who'd otherwise not be able to access banking services.

>What would happen if they skip/delay the reporting part?

They wouldn't. Typically banks take the approach of filing as many reports as they can. If you're overeager in filing the reports, nobody will look at them and you will not be blamed for not filing those reports.

Google for something along the lines of "suspicious activity report flooded" and you'll find endless stories demonstrating how ineffective these systems are.