> Let's say that instead of taxing carbon, we pay people a bonus for emitting a below-average amount of carbon (proportional to the amount that they are below average by). If the amount is in a certain range, it will be too small an amount for wealthy people to care about, but large enough for poorer people to do things within their means (e.g. carpooling) to try to get it.

So you're saying that the government should incentivize poorer people to sell one of the last bits of their functional autonomy for what would be trivial amounts? "We'll just hang onto to this for a bit until you decide to stop going anywhere or make friends at work".