Thats definitely a challenge for them. Crypto can only be used for money laundering if they fail to regulate it effectively.
Leading countries have already shown the way: they enforce strict KYC processes to verify users and ban platforms they cant regulate. Theres already a blueprint in place, so it shouldnt be a big problem as long as they follow what the major countries are doing to combat money laundering.
Its just a matter of proper implementation and consistency to ensure the system works.
I think you simplifying too much: it's impossible to regulate everything, people who want to use some asset to pay or receive money for illegal activities will always find a way, the fact the exchanges ask for KYC helps but within certain limits, it's a deterrent, not a bulletproof solution. And I also doubt that criminals buy cryptos on regulated exchanges.
Policies arent really designed to eliminate problems entirely, thats impossible. Theyre more of a deterrent (agree with you), which is why rules and standards are always in place. For example, if the US has the best methods to combat money laundering, others will just follow that system. Over time, if improvements are needed, they can implement changes.
Its always better when action is prioritized over talk. Finding effective ways to address the problem and acting on them shows real capability in handling these kinds of issues, instead of just talking about the problem so much.