I understand your point, but you're assuming two things.
1. The German product is mostly foreign, but has enough domestic content/transformation to qualify for "Made in Germany" requirements.
2. That the unqualified "Made in USA" is truly genuine.
Neither may be the case, and if you're wondering if any US company would dare violate this, it's happened.
For the most part, the FTC is only interested in ceasing inaccurate claims, though they technically have the ability to levy punitive fines if they fail to prove the unqualified statement. Source.
Unfortunately, they've only levied punitive damages in a single case, which was against Stanley. With the punitive fines at a whopping $206k fine back in 2006. Big whoop.
Nothing more than a small tax really, so if they can still make money while being caught, why would they change how they're doing business? Even prescription drugs that have been pulled from the market in recent years made tons of money, even after the fines and damages they had to pay.
Granted, I don't know how many cases there are or how they were adjudicated, but how many others have slipped past (no case ever brought), or are currently involved in such actions without an inquiry? Particularly as these determinations only result when a court case is filed against a manufacturer as a means of injuring their competition (takes money to litigate this stuff) since express or implied COO can have marketing implications that increase sales.
And lest we forget, there's always wiggle room in US statutes without technically breaking the law (regardless of how immoral it is) given terms such as "all or virtually all" or "significant transformation". What is a fact, is there's no set percentage for most goods at all (75% was proposed, but not included in what was actually passed; source), let alone the requirement to disclose it.
It's not as simple/"cut and dry" as your post is indicating, and this isn't even covering qualified claims, which would be a better comparison to German or products from nations that have a legally defined, but low content % requirement similar to Germany, and are sticking to near, or at the minimum value of that limit.