Yes, Plaid clearly has different levels of integration with different banks.

When I connect something to Chase with Plaid it is clearly a cooperative system with an OAuth-like permission dialog, and the Chase side even mentions they're tokenizing the account numbers so Plaid can't see them.

When I connect to the little bank down the street I just get a username/password dialog. Their web banking system is so primitive I'm pretty sure Plaid is just scraping it. When they introduced 2FA, Plaid became quite flaky.

Correct. They’re incentivized to try to make it as seamless and secure as possible for the 95%, but it’s challenging to build custom integrations for thousands of institutions. Wouldn’t open standards be nice?