Your remark on buses being hampered by sharing the road with cars is on point.

I've lived in Porto, and Malmö. Both have done considerable efforts in making certain roads or lanes exclusive to public transportation.

In Porto, for example, these lanes are exclusive to a very interesting set of vehicles: buses, taxis, and motorcycles. It makes a lot of sense, this way you make riding a motorcycle safer (less vehicles), while preventing bus lanes from blocking all other manners of transport.