There is an interesting correlation I have noticed. In various threads on this forum many users have expressed their opinions about standard transmissions vs automatic transmissions. To a large degree those that favor standard transmissions and the driving experience are the ones denigrating FSD technology, and projecting their views of the market onto the entire market. The penetration of automatic transmissions into the US marketplace is an indicator that there is a flaw in this perception.
More on topic, I definitely agree that the task of FSD could be greatly simplified with external infrastructure. The version of FSD envisioned by GM in the 1950s (implemented only on limited access freeways with guide wires in each lane, and no human driven cars allowed) could easily be implemented today. Whether it is impossible without external infrastructure seems to me to be an open question, and one that has both technical and social content.
The required performance of an FSD vehicle is largely a social issue, as indicated by all the discussion of liability and whether FSD has to be merely better than the drunks and otherwise incapacitated drivers that inhabit our roads, better than the average driver, or substantially better than the very best drivers. In my circle of acquaintances opinions on this subject vary widely, and with a noticeable trend in acceptance of FSD among the younger members of that group. Which indicates that even if the answer were sorted out today, there is real potential for change over time. That difference in acceptance is likely regional also, as indicated by the widely different acceptance of automatic transmissions in different parts of the world.
This social acceptance thing has other parameters. The Teslas driving into the backs of vehicles gets lots of attention, and it is often stated that it is something a human driver would never do. But a close personal friends wife did just that, and a few minutes searching on YouTube will surface many other cases people driving into the backs of construction vehicles, service vehicles and police cars making traffic stops. While it is obvious that a fully attentive, cautious and capable person wouldn't do these things, no one is constantly fully attentive. Our perceptions of what people do are often not data driven.