It doesn't take 20 years for humans to train new tasks. Perhaps to master very complicated tasks, but there is many tasks you can certainly learn to do in a short amount of time. For example, "Take this hammer, and put nails in top 4 corners of this box, turn it around, do the same". You can master that relatively easy. An AGI ought to be able to practically all such tasks.
In any case, general intelligence merely means the capability to do so, not the amount of time it takes. I would certainly bet a physical theorist for example can learn to code in a matter of days despite never having been introduced to a computer before, because our intelligence is based on a very interconnected world model.
It takes about 10 years to train a human to do anything useful after creation.
A 4 year old can navigate the world better than any AI robot can
While I'm constantly disappointed by self driving cars, I do get the impression they're better at navigating the world than I was when I was four. And in public roads specifically, better than when I was fourteen.