I suspect the answer is because they're being remotely monitored and operated 24/7, and they don't have the staff to tend to them.
But only Tesla knows, and they've spent the last few years absolutely destroying their reputation. They lie constantly, they show flagrant disregard for the lives of their customers, and I trust nothing that they say.
EDIT: lol, looks like I was exactly right. These fucking clowns: https://www.wired.com/story/tesla-says-its-robotaxis-are-som...