Heavy commercial vehicles do the most damage to roads, not light vehicles owned by private individuals. If governments really wanted to be effective, then the VMT would be applied to commercial vehicles only, and at a rate that corresponds with the wear they do to the highways.
Eventually, state and federal VMT's will be the norm, in addition to the existing fuel tax. Who know what the average combined tax of the two will be. If it's .30, then a friend of mine is looking at an extra $30k a year in tax.