It probably come out wrong.
what I meant whit this
> removing traffic lights would drive cars' average speed up
is that knowing that cars are slow because there are a lot of traffic lights to stop at, it's not very helpful.
The only thing that we can logically conclude with that information is that traffic lights take down average speed.
On the other hand, being bikes' top speeds much lower than cars and being subject at the same traffic lights, the only thing that we can conclude is that they don't stop at traffic lights as much or they pass cars stuck in traffic, even if it's probably forbidden.
Which is okay, everybody does that, but, again, not very helpful.
It only says that bikes don't respect every traffic laws in the book.
Not a big deal, but we can't use that information to optimize traffic.