Earlier quoted context omitted.
As a robotics person outside this space, it's not amazing that the shift to L4 as a goal has not been clearly grok'd by the public. After years of rhetoric, most people still believe that cars will be fully autonomous because they just don't understand the limitations. It's also quite amazing to me we, the so called smart ones, ever believed level 5 was happening but those were the good old days, huh.
It's hard to impossible for me to know how difficult level 5 driving even is since we don't have any machine that can do it. Trying to achieve it has been a good example of turtles all the way down. At the same time I feel like people are ignoring how well self-driving works RIGHT NOW, the rate of accidents is still less than with human drivers. So I'm still pretty optimistic.
I have slightly a different opinion. I think you can easily guesstimate how difficult something will be by listing the "new" stuff. But I think you can't easily estimate how easy something will be because you can't list everything, so anything you miss could easily delay.
Said another way: We should have known it would take at least a decade, but should never have said it will take at most two decades. (as technologists).
And yeah - agree - lvl 3 is pretty good, feature-wise.