I'd rather see a carbon tax than eg photovoltaic subsidies.
The latter requires picking winners, and the recipients need to interact with bureaucracy to claim. The former rewards simply consuming less just as much as eg switching to renewables; and you don't need a lawyer to claim your (relative) rewards of lower taxes.
You can tie subsidies to the "amount of CO2 spared compared to the average". Carbon tax creates the moral hazard of normalizing pollution, as long as you pay your tax.
But due to the higher costs, all but the wealthiest will be "forced" into making changes to their patterns. There was a recent Planet Money episode about these Pigouvian taxes[1].
"[A]mount of CO2 spared compared to the average" seems to be hard to define: if I burn lots of natural gas to create electricity, I release less natural gas than if I burn coal. But I release more than if I had managed to make do without that electricity.
But yes, a carbon tax is exactly that: if you pay your tax, releasing CO2 is legally and morally fine.
There's a certain amount that we can safely release. (That amount is smaller than what we release today.) The climate doesn't care about who's releasing CO2. So we use willingness to pay taxes to ration out that limited supply of allowable CO2 emissions.
Eg your fear seems to be that rich people can just buy indulgences and keep sinning, instead of having to repent? I say compared to giving every person an equal share of allowable emissions directly, I'm happy to personally emit a bit less, and have some ultra rich person indulge in return for them paying crazy amounts of taxes. I don't care about their moral fibre as long as they pay up.
If too many people decide to just pay the tax instead of cut their emissions, we'd need to adjust the tax rate. Because of inflation, population growth, advances of science etc, we would want to revise the tax rate every once in a while anyway.
(A cap-and-trade system would do that adjustment of the price automatically, but it seems that in practice it's hard for politicians to refrain from handing out permits for free and handing out too many. Eg the EU system would have worked better, if all permits would have been auctioned off by the government instead of being handed out to previous polluters for free.)
The 'opposite side' of that is also true:
I'd rather see a carbon tax than eg photovoltaic subsidies.
The latter requires picking winners, and the recipients need to interact with bureaucracy to claim. The former rewards simply consuming less just as much as eg switching to renewables; and you don't need a lawyer to claim your (relative) rewards of lower taxes.