Perhaps but in the marginal case (Ie. for a company which is just on the edge of using a FOSS product), this could screw everybody over.

Only if they're clueless enough to not understanding the licensing. If you're basing your business on something, you should understand how it works, licensing included. It's really not all that difficult, and if you have doubts, there are tons of people you can ask for help. I've done a bit of that kind of work for pay in the past, although I obviously avoid actual 'legal' questions. I wouldn't mind getting more, but I don't think that it's that common, as it's just not that hard to understand, and there are tons of people who will answer questions for free.