That picture doesn't make sense, because cars don't drive that close together, nor do bikes ride that close together.
Show 60 cars at 45 mph vs 60 bikers at 15 mph for a better density view.
Show 60 cars at 45 mph vs 60 bikers at 15 mph for a better density view.
https://bicycledutch.files.wordpress.com/2013/03/amsterdam.j...
In my experiece they absolutely do, but it is rare to see a big pack together.
Objects moving 3x faster can be 1/3 as dense and have the same overall throughput.
(You can argue that people don't usually leave sufficient space to stop, but I will point out that self-driving cars, which prompted this discussion, are going to be following those basic safety rules)
Your complaint is that cars lower density as speed increases, which is true, but you're still looking at this too narrowly. Consider the bus.