Cars are inefficient at moving people

From this picture [1], you can see how cars move people the least.

There’s also a good video where it compares 5 modes of transports with 200 people each where cars is the least inefficient method of moving people [2].

This is further exacerbated by people not filling up cars to it’s full capacity. In the United States, average car occupancy was 1.5 persons per vehicle [3] while the most recent data for the average number of passengers per car (including the driver) for the countries sampled is approximately 1.45 passengers per vehicle (in the UK - 1.58; Germany - 1.42 and Netherlands - 1.38 passengers accordingly) [4].