Beautiful and succinct. I tried to relate that point above but you did better than me. It's laziness on the part of the companies and it's not excusable. Just because you use some fly by night Chinese supplier doesn't mean you as the distributer that got a product for half the cost of a proprietary one aren't on the hook.
Violations should have penalties so that companies realize GPL code has a compliance cost that needs to be accounted for, tracked, and followed up on including putting those same requirements in their supply contracts. It's simply negligence for them not to comply then claim it's not their problem. Not a single case has gone to the jury because once legal actually gets involved and runs the cost they realize that failing to settle will cost them far more than any of the costs SFC ask for. When you want to pay nothing SFC's costs might seem high, but in comparison to those proprietary solutions or a jury ruling of infringement it's pennies.