The UK happily lets in an estimated 90 billion a year of dirty money to be laundered in the City of London, and all we need do to stop it is enforce beneficial ownership registries.
The US holds non US transactions to a higher standard of proberity than onshore (foreign corrupt practises act)
I am still guided by two principles on this - that complete openness and transparency solves 80% of problems and rigorous competition solves the rest (my favourite phrase - a billionaire is an example of market failure)