The news has been spamming PR pieces for years about self-driving cars, with absolutely no technical merit to them. Twitter/Reddit/Etc have been absolutely spammed by echo chambers that all assure themselves that self-driving cars have been invented and will be released soon.
The population is awash with the viral idea that they're possible, exist, and are on the way, because that's just what they've been told for years. The average person repeats the idea because that's what the internet told them is true, which makes it even more "true", since now there's another person repeating it.
What percentage of the population that goes online and talks about how self-driving cars are coming soon actually have the engineering background / technical knowledge to come to that conclusion?