"because not enough people will care enough to pay for the price difference" the emissions are invisible, and thus people don't have the choice whether to pay more or not.

Especially as a lot of the consumption is indirect - you don't buy the gas, but you buy a meal in a restaurant that was cooked using that gas, or a car whose manufacturer bought the dashboard from a company that bought the plastic from a company that made it using gas from the national gas market, where all gas is fungible and it doesn't matter how it was produced.