They arrest them and prosecute them through the courts. I just gave you an article with many arrests in the USA and India.
Using your logic we should ignore all crime! Once again read the article I linked to, they go after the top people and they are given sentences of around 20 years.
And as I said they could block all traffic from the scammers very quickly
There are no votes in taking action, only a small percentage of people are affected and Australia is utterly and totally useless in prosecuting any crimes like this and always has been. Look at the huge problems with scammers (Gumtree, eBay, driveway resurfacing and roof repairs to name a few) coming here on VISAS that the police do nothing to address, look at the ongoing issues that have been common since early 2000’s with credit card fraud and eBay. Has anything been done? Nope. Our police investigate very little crime and the criminals know that Australia is a soft target.