<<off-topic>>
OK, how does one compile street maps?
Method 1: you go around and survey the town, and draw your own map.
That's how'tis done, in a team, at mapping parties. It looks rather funny, sometimes downright suspect, while gathering the GPS tracks. Afterwards, when the tracks are uploaded and streets are drawn from them, it is very nice to see the streets coming together bit by bit.
In this last step, existing maps may be used as a secondary source of information; but I have on at least one occasion introduced bad data by blindly believing a commercial internet map provider. Better secondary data comes from one's photography during the gathering, and from official maps, e.g. at the municipality.