Simply it’s known as KYC. It’s mandatory for all financial institutions (FI) and their customers.
The FI need to know the source of funds (if there aren’t illegal) and to avoid money-laundering activities and terrorism financing, just to simplifying the whole process. The FI are required to do that by the financial regulators and the local and international legislation.
I would be more worried if some FI didn’t ask that or didn’t do KYC at all. That means that they aren’t following the regulation and legislation. Creating a potential risk of being fined or even closed by the regulators. The suspicious players generally choose the weak KYC platforms due to that, posing a great risk to the other investors that are honest, risking their honest earned money.