Wait. I'll just check with our resident digital currency experts and get back to you. Sciforums, after all, is nothing if not a site for learning how to buy, sell and trade digital currencies. You've definitely come to the right place with your questions! Stay tuned.
https://www.bbc.com/news/business-61090064 US cryptocurrency expert jailed for helping North Korea evade sanctions
Coinbase and Binance are primarily exchanges. That is, they facilitate peer-to-peer trading. When you want to buy, they link you to someone willing to sell at the same price, and they take a small cut of the trade value (from both the buyer and seller). They do own some BTC themselves (I think Coin own c.5,000 BTC or so) but that's really just a float. If you buy some direct from them (at a higher fee), they will then buy BTC from someone else. So the end result is much the same as a more direct exchange, but more expensive for the buyer/seller as they're both trading directly with Coinbase / Binance rather than between each other. Hope that answers your question.