I deal in high end pro audio equipment. First off, it's kind of easy to see who is a freight forwarder. There's entire city blocks where if I get an order there I know what's going on, and Google Maps doesn't hurt. Plus when someone puts 123 Meryl st box 929183, it's pretty evident. Not to mention an international card has to go through more verification processes because the bank will not verify transactions with US merchants.
Second, most of my manufacturers will not honor warranties on grey market purchases (things purchased in one nation and shipped to another). I'm banned from SELLING it internationally, not shipping it internationally. And yes, that's a finite difference, but it's there. If I do so, I can lose my authorization as a dealer for those manufacturers. So yes, I'm in a bit of a different situation than most. Most of my vendors turn a blind eye to it, but there's a good chunk of them that do not. Some see it go to a freight forwarder and are okay with that, but others see it and will put me up shit creek without a paddle. Regardless, international ordering is always tricky, and most of my Aussie customers see the warranty stuff and freak, not to mention the fact that I can't get equipment in their voltage for the most part.