How are illegal activities prevented?

“Crypto for Beginners” course mentions how blockchain transactions cannot be censored and are decentralized. Also, anyone can participate without ID verification, credit check, etc. The simple and natural question in my mind is the one is the subject. I am thinking of anything from money laundering to gun trafficking or hush money and/or payment for illegal services. If all you need is the possession of some crypto for collateral to be able to make payments, then aren’t we opening a whole new and very easy way for criminals to execute business transactions? Thx in advance!