Yeah, speed is unfairly blamed. Just look at how safe the German Autobahn is.
Americans spend ~70,000,000,000 hours driving per year already, according to https://newsroom.aaa.com/2019/02/think-youre-in-your-car-more-youre-right-americans-spend-70-billion-hours-behind-the-wheel/
If the hypothetical 20 miles/hr policy only resulted in travel times doubling, that would be an extra 70 billion hours wasted, or just under 200,000 lives per year wasted (assuming 40 year remaining lifespan).
It would, in all likelihood, be much worse, because fatigue is implicated in more fatal crashes than speed already, without doubling travel times.
People suck at judging risks when making choices, but they attempt it sincerely because they have "skin in the game".
Individually more intelligent and better informed experts make everyone's choices for them even more poorly, because they have no skin in the game and are rarely/never held accountable for externalities.
