The trick here is that high income people can purchase emission credits by dumping their emissions responsibility onto someone that produces little to no, or even negative emissions, which lowers their responsible emissions.

Many companies do this. In tech, vehicle manufacturing, oil refineries. Hell, even entire countries does this. It doesn't lower the total emissions, just dumps the responsibility for the emissions onto someone that produces very little emissions, which lowers the purchaser's emission responsibility and increases the seller's responsibility. Usually the seller of the credits only buy up so and so much to avoid paying emissions taxes or getting sanctioned and taxed in other ways.