Are ferries considered limited in their ability to manoeuvre?

I know a number of places where ferries behave as if they could not alter their courses and they Stand On no matter what. I think they base this on the fact that they are like trams or trains, their designated courses are mapped on the chart and they can not deviate. Similarly, some passanger boats in general tend to do the same, claiming that because they have an official schedule, they can not afford altering their course or speed. Some examples are hydrofoil passanger boats in Italy, Jadrolinija boats in Croatia, ferries on the Balaton lake in Hungary. Of course in practice you know this and you do what you must avoid them, but I would be interested how COLREG should really be interpreted in this case.