In large organisations, the effect of employee lawsuits may even be beneficial, because it allows for a mechanism to escalate serious issues before they become even worse, while the high barriers in terms of cost, emotional burden etc. serve to discourage frivolous complaints.

You forget, companies solely consist of people and are solely owned by people. It's a legal vehicle.

People, of which companies consist, have feelings and emotions.

It's their job to make the company look good so it would seem logical they would want to try and get this water under the bridge.

If they thought it was valid, it seems the PR team would push for settlement without admitting wrongdoing but if they really do believe she is out on a limb, firing her does seems like the go to option and let it go to court to try and clear the charge.

Its very hard from a legal perspective to establish "beyond reasonable doubt" (or even "preponderance of evidence") with just the word of one person. You would probably need something else too.

Who's responsible for the problems again?

When the company "said" they were unmerited, that is.

Well, she might think that the company would be loath to compound it's legal issue by illegally retaliating against her for the harassment claims. (And it's illegal to retaliate for such a claim made in good faith even if the complained-about conduct does not actually create liability for harassment, so Tesla could potentially be liable for retaliation even if not liable for harassment.)

Because she's not independently wealthy. And she's perfectly aware of the negative impact on prospective employers' willingness to hire here -- until and unless she's fully vindicated, at the end.

That question is probably easier to answer for Tesla than for any other company: It's the place to be if you're any engineer with an interest in renewable energy.

It'd be a tragedy to tell people they have to chose between freedom from sexual harassment and fulfilling their professional aspirations.