In the US because roads are built to maximize vehicle throughput rather than throughput of people. The former would have 2 lanes with cars and buses using all t

In the US because roads are built to maximize vehicle throughput rather than throughput of people. The former would have 2 lanes with cars and buses using all the road space. The latter would have a massive traffic jam in one lane and a clear land for buses. The buses carrying 30x the capacity moving freely is more efficient for moving people.