In the game code you will find some interesting texts which tells that there was an option to enter and leave buses which means that Vito was originally able to travel by taxis, buses or even use subway to get where he wanted.
There is a speculation that Tobacco shops in Empire Bay were selling newspaper with bus routes around the city.
Remains of this can be found in:
ENTER_BUS 00_57_00_0036:Bus Stop
Note: it's possible these relate to Vito going to prison.