When the parts in its cars work well, does Tesla give the suppliers the credit? Tesla is very good at PR, if not parking brakes. The faulty parking break is from Tesla, not the supplier; Tesla is responsible for the car, including all parts from suppliers; it's Tesla's responsibility, technically and legally, to make sure the part works properly. Any engineer would (I hope) be embarrassed if it was suggested otherwise about their work product.
I would be ashamed to deliver something to a client and blame a supplier for a problem. It implies that I'm not in control and that worse, I don't understand that I should be in control and my fundamental responsibilities, and that I lack judgement. My client couldn't care less why my product has a problem; from their perspective it's my fault - which is true and exactly how I want them to think.
I'm sure the supplier could blame their suppliers, who could blame yet more.
In some cases that means that company representatives are found dockside inspecting containers and taking samples before they are being loaded.
Also it's a very rare problem, so it's probably hard to find in QA.
People (maybe not you) are still interested in the source of the problem, but it's an ortoghonal question.
Takata airbags got the PR damage, even though its airbags were installed into Ford / GM / etc. etc.