The proposed sales tax is a poor tax not just in that it affects the poor more than the wealthy, but that it's a poorly conceived tax. It relies on sales, the idea being that people will supply more funding as they buy more gas (and most other items). It does not, however, account for changes in prices. A sales tax on gas would currently bring in less money than it would have a few years ago. While the price of gas may go up in the future, the increasingly volatile nature of oil prices does not make this a "fair" tax. [Side note: I would like to see the increase to school funding and the return of the earned income credit that are proposed in the current sales tax, but this is not the way to pay for them.]
Some people have proposed that the fairest way to tax road repair would be through tolls. There are two problems with this. One, the cost of the infrastructure to set up a toll system is too high. Two, Michigan is a peninsula (well, two). People don't need to travel through it the way they do most states with toll systems. Putting a toll on our roads would only make more people go around.
While I believe a good deal of Michigan's problems are due to mismanagement of business incentives which have done little to stop the flight of people and talent from the state, simply getting rid of them is not, in my mind, a fair or sustainable way to deal with the upkeep of our roads. That said, Michigan's current "pro-business" atmosphere has only helped the wealthy in Michigan. "Trickle down" economics is consistently proven to not work, but that is a topic for another time.
Putting a tax on the volume of gasoline sold is the fairest and most sustainable way to provide funds for our roads. A tax on volume is not dependent on the price of oil (and thus gas). It puts more of a tax on the heavier vehicles that do the most damage to our roads. It serves as its own sort of toll without the trouble of tolls. It affects people who travel through the state, not just those who live in it.
Some of the above benefits are benefits from other forms of revenue, but not all of them are together like they are in this kind of tax. While this can have its own trickle down effects on consumers (higher gas prices will make goods transported on the roads higher), by not being dependent on the price of gas, it can take advantage of (and even encourage) lower gas prices.
Concerns about this kind of tax (other than higher food and goods prices) most often stated are focused on fuel-efficient vehicles and people buying their gas out of state. To the first, we should encourage the use of fuel-efficient vehicles (the current tax proposal actively discourages them), they don't do as much damage to our roads due to their lighter construction, and they already bring in more revenue through the current sales tax as they tend to be more expensive to purchase. To the second, Michigan is a big state. People might get some of their gas out of state, but if they are driving on our roads long enough to wear on our roads, they will be getting gas in our state as well.
Governor Snyder said that there is "no plan B" if the proposed sales tax doesn't pass. That shows a lack of leadership and planning on his part. As he hasn't been able to come up with one on his own, I give him full permission to use mine.