We can debate the meaning of “truly autonomous”, but the Tesla-owning friends and acquaintances of mine have all, without any uncertainty, recently commented to me that the top-tier self-driving plan in the modern Teslas is just that.
One frequently uses it to drive from his house in LA to San Jose, another from Philly to Boston, another from Kamloops to Vancouver (Canada). I personally have never experienced it, but I trust their word and experiences enough to believe that it is at an extremely high level of capability.
Today, Tesla's so-called full self-driving system is legally classified as SAE Level 2 driver assistance [1]. The human driver must continuously monitor the system, be ready to take over instantly at any time, and is legally responsible for the the car. Tesla is careful to avoid any liability for this by stating this somewhere, perhaps in a 3-point font.
Even if techbros loudly insist that they can take a nap in the back seat, that doesn't change the legal facts. Just like a drunk driver confidently shouting that he's totally fine to drive.
Highway driving is a bit different from complex city conditions. Just look at the difference between the telsa robotaxi performance vs Waymo. Only one of them is truly FSD.