That's an interesting question too. I suspect incentives would be far better without speed limits and instead using insurance, liability, & road/space design to align driver and incentives. Its actually a massive state created problem that roads and inner cities have done top-down development that put the car as the focus of movement. Its destroyed the connection of local community and made people aggressive drivers who treat pedestrians not as the prime owners of the space, but as a nuisance. It literally leads to the type of behavior that makes the roads dangerous and makes people feel that they "own the road" while in the car and that everyone else is getting in their way.

The autobahn is a decent example of how the lack of speed limits and arbitrary punishment don't create disaster, it creates a different, more natural order. then another great example is a packed city that had an experiment in a small area that was hugely disconnected because of a big intersection and busy multilane road that created a huge division between major blocks -- they took the huge intersection and made a round about, and they removed all of the curbs so the bricked sidewalks merged right into the road. The only separation was difference in material. Basically overnight the community got hugely more connected, the pedestrians were way safer, the drivers were more aware, the intersection wasn't constantly packed with angry drivers, and foot traffic for business on both sides of the road sky rocketed. It literally transformed from a road that disconnected people, to a communal space.

TL;DR, design and natural development are far better at producing positive incentives and aligning behavior than top-down "planning" and broad sweeping rules and punishments.