Sure! Both speed and distance matters a lot for throughput. The advantage of pedestrian traffic is that designing for it reduces the distance people have to travel and that it combines very well in conjunction with public transport, unlike cars. Also, the speed of mixed traffic is inverse correlated to the number of vehicles, hence is a special case in this regard where throughput may decrease as the volume per lane increases. The overall point however is that a single train can substitute a staggering amount of private vehicles (and who doesn’t love leaning back, listening to music and reading the news while commuting?).
Well, no one is saying cars are worse for all purposes. If you want to take your family and dogs to a cabin in the mountains while also shopping for food along the way, it is probably going to be your best bet. Still, that is not what is pictured in the post. These are commuters that are probably moving from work to home (or vice versa), where cars really are the worst of most options. If the bus takes longer, it is probably an issue of allocation of funds for a shorter route and exclusive lanes for it.