What are the criteria that go into quantifying interior build quality?

Tesla's interior is definitely spartan, with things like center console and extra cupholder set available only after-market, but that seems to fit into the story of "design the most lightweight vehicle possible in order to increase the range".

Are there reports of numerous interior-level problems, like fobs or panels or lights or switches falling off, etc.? Because honestly there's not much of "interior" there to discuss its quality.