The one that where mass transit works better.
But yeah, a city still needs cars, and roundabouts are still unbeatable in low-traffic crossings. But they are not the most impacting change a city can make.
However, crossings with traffic lights I can take at any speed I'm able to, when they are green for me, and I don't need to turn. Or if I can oversee them from afar, and they are empty, and I can give a shit about 'lights'.
Other than that it's obviously by design. There is no reason to speed at constant 50kph in a city. Nether for a car, motorbike or e-bike.
Which does two things, raises state revenue and causes drivers to spend way to much time concentrating on how fast they are going rather than driving to suit the conditions and paying focusing to what’s going on in front of them.
And don’t get me started on the pot holes.