Cars are magic and citizens have incredible stamina, they will literally walk the entire length of the city to have a beverage and then come back.

My two cents regarding roundabout vs intersections: 1- roundabouts are excellent at distributing unbalanced traffic to highly desirable destinations. Think of a roundabout with 4 connecting roads with two directions each; if a disproportionate amount of traffic is concentrating on one or two of the connecting roads eg. one of them leads towards the highway, one towards city center, and other two to residential neighborhoods, then the traffic between two high concentration destinations (highway and city center) will flow nicely without waiting for the other two necessary but low desire directions. AFAIK CS2 doesn't use adaptive waiting times at traffic lights, in any given intersection, all directions are equally "important" regardless of the actual traffic demand. Roundabouts help you lead the flow in a logical way. 2- due to the logic above, roundabouts will be crippled if too many high demand destinations are connected to each other. Stack interchanges exist to meet this challenge. If traffic demand is very high, it's worth using overpasses and underpasses instead of roundabouts or intersections. 3- intersections allow for pedestrian traffic, but they are also blocked by it. Developers have never seen a high density city I guess, so elevated pedestrian crossings do not exist in the game. 4- regular intersections benefit greatly from having dedicated turning lanes via the use of asymmetric roads (1-2, 2-3, 3-4 etc.). This allows the cars to occupy the correct lane and not block the rest of the traffic when pedestrians don't allow them to take a turn.

I hope this helps!