You're right. SoCal summer roads are definitely the easy part. I bought a Comma Eon for a few hundred dollars and it does most of what Tesla's Extended Autopilot does. It's a solved problem, that's relatively inexpensive.
However, if people are willing to pay Tesla $7k for the promise of a "coming" full self driving product that doesn't exist yet, I don't really feel bad for them. It's kind of Tesla's business strategy at this point. I don't think they're acting in bad faith to their customers, because they have a track record of (eventually) delivering great products, but their leadership is unreasonably optimistic. I worry for the future of the company. Whether Musk's isn't living up to his fiduciary responsibilities to investors, I have a lot of issues with... that's a whole separate topic.