These pods are only used on rails with very low ridership. They would switch to a train if ridership increased.

Look at it this way: you can have a train that has a capacity of 100 people, but it only runs once a day due to the low demand, and only 2 people want to ride it at that time of day..Or you can have 10 pods, which do not require as much railway maintenance, and they can carry the 10 people who actually want to use this railway, completely on demand.

Yeah, a train is better if you want to move ten thousand people a day at peak hour. But this is a cheaper way to move ten people at different times across a day. And it's a cheaper way of inducing the demand that would justify the more efficient kind of expansion.