I don't think I'm missing it. I won't rehash a bunch of my comment history on Waymo, but if Tesla can actually do this, without the costs Waymo has, it'll be quite the coup. And as others have pointed out, Tesla already has all the manufacturing in place and though I'm super doubtful they'll offer a "hire your car out" service anytime soon (or ever!) having the whole vertical offering and using fewer sensors puts them at a distinct advantage from a margin standpoint so they could conceivably offer rides at a significantly lower price than Waymo.
Obviously the "if Tesla can actually do this" is doing a lot of work here! I would not surprise me if they had a crash sooner than later and that scuttles the whole thing. But it's also possible that doesn't happen and this works. Or at least I'm not smart enough to know for sure that it won't.