Having driven in the UK and coming back to the US I miss all of the roundabouts. Any reason (aside from contractor profits) towns use 4-way traffic light systems vs a roundabout and some yield signs?
Traffic lights can be tuned to create "green waves" that allows for efficient flow of traffic along arteries through a city. You can adjust the timing throughout the day to help alleviate congestion. In rural areas, heavy machinery/commercial vehicles may need to make a very wide turn through the intersection. Traffic circles are fine for a lot of applications but they aren't strictly better than lights in all circum…
There are also solutions for large vehicles where the center is raised but not impassible.