It seems that the author is thoroughly confused about the difference between city buses and coaches.
First of all, this difference exists only in some add-ons such as
eGRVTS and
Road Hog. Moreover, the distinction is somewhat arbitrary, because from the game's point of view they all are just models of passenger bus.
In general, "city buses" tend to have high capacity and loading speed, but lower maximum speed and high rate of cargo decay. "Coaches", on the other hand, have much lower capacity, but their maximum speed is almost on par with trains (about 120 km/h in later models), and the cargo decay rate is lower.
This distinction has absolutely nothing to do with the types of bus stop. Some of the "city buses" are articulated and thus cannot use bay stops, but this applies to all articulated road vehicles.