Most of the road is only there because people use cars instead of public transport. Keep 2 lanes as necessary,the remaining lanes should be divided among the cars as wasted space caused by them.
Buses need roads too, and train tracks are just as big as roads but less versatile.
And delivery vehicles, emergency vehicles, etc. We certainly had roads before we had cars.
Road that connects 3 biggest cities in Netherlands has 3 lanes in each direction: https://www.google.com/maps/@52.1822053,4.5947627,3a,75y,47....
Your average road in Netherlands looks like this: https://www.google.com/maps/@52.1968565,4.592548,3a,75y,58.8...
You cannot directly translate between countries with such difference in population density obviously, but if anything - the more people USA has - the bigger gains are there to be realized by switching to more efficient mode of transport.
Mind you there's some cars in the videos, but they aren't any bigger than the horse-drawn carriages that roads had been accommodating well before that.
Parking lots and on street parking is a tremendous waste of space (and they're ugly to boot) and forces EVERYTHING to be more spread out.
That's why I said keep 2 lanes (1 in each direction). Anything more is optional and should be counted as effect of car-centric development model.
> train tracks are just as big as roads but less versatile
1 railway track in each direction gives you more throughput than any multi-lane motorway possibly could.