I think this is a fundamental misunderstanding of what short sellers do (which is where most of the "fraud" accusation comes from). Some short sellers DO claim fraudulent behavior, e.g. Enron was famously predicted to be fraudulent by Jim Chanos.

However short selling at its core just involves the belief that a company is overvalued. In the case of extreme fraud, the "correct value" is $0. In most cases, the short seller just believes it's some amount less than the current share price (but above $0).

Tesla falls into the latter category. I'm sure some do claim fraudulent behavior, but Tesla is an interesting case because Tesla's PE is ~200 IIRC, compared to the 20 average for the automotive industry. For comparison, Amazon's PE is 120.

So if you think Tesla is ultimately a car company, or even just a "regular" tech company, it's not insane to think that it's incredibly overvalued. That doesn't mean you think it's a fraud, of course, but the subtlety obviously gets lost by many (and short sellers often make grandiose edicts that don't help their case).