Law can't be enforced because some powers don't want that. What about money laundering that could get hidden within seemingly legit transactions for multi billo

Law can't be enforced because some powers don't want that. What about money laundering that could get hidden within seemingly legit transactions for multi billon dollars companies? Wouldn't be abusive if they try to regulate the behaviour of people buying online? How do they know the way to conduct that kind of investigation? Doesn't seem realistic.