I'm not disagreeing with you at all, I think it needs to be reduced, but of that 27% (per US gov stats on CO2 for transportation) only 41% is passenger cars. So really, passenger vehicles are only 11% of CO2 emissions. It's not nothing but it's also not the largest contributor.

Point being it can be nonzero and still be effective. We don't need to ban all ICE options, we just need most people to move to alternatives so that the few people who have legitimate need for ICE can still use it.