> 2. Certain political elements are always trying to defund the tax auditors (e.g., the IRS). We might well ask why that is.
Tax the petrol itself. That works reasonably well in most of the world. No need for complicated individual audits etc.
> 3. Politically, tax hikes are always harder to get through Congress — and to keep in force — than sensible standards for products and behaviors that voters can see are beneficial to them (e.g., pollution prohibitions).
I don't know. We kicked off the whole discussion because the standards you have are NOT sensible.
True — but see my #3 above (political problems), and then add 3.1: Special-interest groups, which donate heavily to politicians' campaigns, always lobby for tax breaks of various kinds, e.g., tax deductions (at the federal level) for state- and local sales- and property taxes.
1. People — individuals and companies — game the tax system at least as much as they do pollution regulations.
(As part of that effort, certain political elements are always trying to defund the tax enforcers (e.g., the IRS) so as to make it easier for scofflaws to get away with such gaming.)
2. Politically, tax hikes are always harder to enact — and to keep in force — than standards for products and behaviors that voters can see are beneficial to them (e.g., pollution prohibitions).