Yes literally impossible to take something in a format legal in the US, that doesn't match the foreign requirements, based on European testimony above (the exact truth of which IDK).
Informal tax-evading (when the seller isn't evading, just the buyer) doesn't require personal contacts. This is just naïve thoughtless statement. It happens all the time. Example: business owner goes to Panama where they know no one. Buys a pallet of llama wool, seller gives a non-conforming receipt. Buyer goes back to France, imports the pallet as "cotton" and creates a fake invoice showing the Panamanian sold cotton. Seller then sells llama wool on the streets for cash, marking in the books that they sold "cotton" for significantly less. They then use the on-the-books "cotton" proceeds to buy a shit-wagon car or something, and fix it using the unrecorded cash on the side. They sell the now nice shit-wagon and record the proceeds as profit. Now all the money for the llama wool is accounted for.
Cross country tax-evading is only assured in this case to require personal contacts when the tax evading happens on _both_ sides. When it only happens on the EU side, there's no need for personal contacts on the US side.