Pay per mile is a bad idea.
In fact, they will pay. More, inevitably. Because pay-by-mile taxes, like all taxes, go up rather than down and in this case, are certain to go up even more than gas taxes, which are held back by dint of being more noticeable. Every time a person buys gas – which for most people is at least once a week – they are confronted with how much they are having to pay for gas, plus tax. Taxes are already so high on gas (and diesel) that even small upticks are usually met with vociferous opposition. This is why gas taxes haven’t gone up that much over the past 20 years even though the cost of gas has more than doubled over just the past two years.