Because the tarmac is empty does not mean the people and nature living around the roads are gone. Whenever resource sharing with other living creatures pops up in America it somehow gets turned into a 'blind policital statement'.
If you want to reduce the number of cars on roads - which is a sensible approach - you reduce the need for cars. The easiest is to not mandate people to work in offices where not needed. By slowing vehicles down you achieve a placebo effect since said vehicles would be slow anyway when there’s traffic, while they’d be needlessly slow when there is none. Spending more time driving slowly means the same amount of noxious gases being emitted - even if emissions per car are lower, given that they spend more time on the road you gain little benefits.
However safety benefits and noise reduction are an asset. But those can easily be reduced in better more environment friendly ways.
