The comparison between what cities is interesting. The vehicle license fee is more direct, as it's visible, and that particular city's residents pay. The sales tax is more indirect-in terms of visibility, i.e. most people don't notice it nor know why it's as high as it is-and is borne by non-residents as well. A mild justification to go the sales tax route could be made for cities with high "pass through" traffic, but I think the VLF is the better way to go, because it's up-front.