I've never understood why, when it comes to passing laws, the 'majority' are not criminals and want the new laws, but the reason they say they need the laws is because the 'majority' are pirates and are killing their business.
What you're missing is that "mainstream" is changing. Before, the labels controlled who received the most airtime and who got the most advertisement. Thankfully, to many of us, that is changing. Some people like to have a choice in what they listen to and not be limited to what the labels think we should hear.
If you think about it, it doesn't really matter if they can prove it. They can drag you into court and make it last years, costing you a lot more than a settlement would. Guess what most smaller companies would probably opt for?
The problem is, that won't solve the problem. You don't have to use Microsoft programs/hardware/etc. to be sued. You can have zero Microsoft products in use at your shop and STILL be sued because you bought something to use in your business from someone who used pirated Microsoft software. Your hands can be completely clean of any piracy but you can still be sued and have to pay Microsoft.