I intended for “risk” to be short for “safety risk” in the below portion of my original comment:

> Taking advantage of the gaps actually increases the road’s throughput, and is a sufficient tradeoff to risk and energy efficiency for almost all drivers worldwide.

> the road can handle you must not put more cars into the empty space without all the cars slowing down (which in turn means the road can handle less cars per time)

I agree that there is a range where cars weaving in and out causing people to brake unnecessarily causes more congestion, but there is also a point where there is so much congestion that “filling in the gaps” becomes the optimal move, because the road’s capacity has been reached and maintaining large gaps would simply push congestion further back onto other roads.