Funding terrorism and tax evasion are incredibly rare. I mean it, not-credibly rare. The main difficulty in discerning that is legality. Is this person/company evading taxes according to the law. Is this person allowed to purchase $5,000 of Syrian saffron on wish.com?

No, I'm afraid governments already track all data necessary to pursue and convict tax evasion and terrorists. We don't need to sacrifice this new, exciting technology because of bureaucratic laziness and FUD. $800 billion defense + $200 billion law enforcement should be enough to track all dozen suspected domestic terrorists in the USA, and Interpol/Nato/EU share technology with the USA.