Its quite common to find commercial copyright infringement in all of those (except for the unreal engine, since I don't know publicized case of that), and there are artists who earn a fair income by contacting infringes and demand payment or a cease and desist. I wouldn't however describe that as being bitten by the rightful author, but put the blame on the developer who is using someone else work without permission, especially if they their own business model is based on copyright.
Just as easily as it is for a designer to use a copyrighted work. The GPL isn't a boogieman, every project that's under the GPL says so. If a developer isn't mindful enough to realise that they shouldn't randomly copy-paste library dependencies without knowing anything about them isn't a very good developer.
That's a logical fallacy called: No true Scotsman. In this case - Good developers can be good at some things but bad at other things, so there's absolutely zero correlation between "good/bad developers" and "people who remember/forget to think about licensing".
In a predatory lending/loan sharking scheme, the lender offers their product (money) to people who need it (borrowers) who must agree to extraordinarily high interest rates.
This seems very similar to the GPL since it's just a software agreement that includes extraordinary clauses for developer who "borrows" the product.
If you don't audit, you don't know if you are in breach of the GPL or not. Your corporate counsel will want you to audit. You can't reasonably take any action, including open sourcing your project or even posting code snippets on a company engineering blog, until you know which licenses you actually use.