A single bus has 25-40 seats, so those other 160 people are going to be pretty miserable.

An articulated bus might be able to move closer to 100 people comfortably.

wouldn't it be more fair to compare a single subway car with a bus? nothing stops you from running a "train" of buses.

It isn't really that fair, the critical time sink starts shifting to offload/onload time and there is a lot of waste having to load each bus individually.

This is why developed subway systems with high usage end up with large trains, that's the best way to speed up the system, reducing the delay caused by trains waiting for other trains that are stopped in the station.

Even a "train" of two buses is impractical for most bus routes because of the weight, poor turning radius and so on. I'm pretty sure going any longer than two is virtually impossible.