@Hartmut *******
An agent who assists in opening a bank account does not inherently break any laws or banking rules.
They simply help the bank internally justify the considerable cost of opening an account for a customer whose stay in Thailand might be so short as to be unprofitable. This is not illegal in Thailand.
When you sell a house, and employ an estate agent to assist, is that a "bribe?"
Do you call it a bribe when you pay a lawyer to help set up a business and navigate the regulatory system? Or when you pay an accountant to file your taxes? Or you pay a concierge to get you unattainable theatre tickets or a table at a popular restaurant?
Or you employ a lobbyist to help you make your case before the government?
Banks are breaking no laws when they allow tourists to open a bank account, nor if they deny it.