As the parent says, the goal is to have NET 0 emissions. Certainly some emissions will still occur but they need to be small enough to be offset by CO2 removal. Because it is almost always much easier to prevent emissions rather than remove CO2, preventing 100% emission from cars and their production is likely to be best path to NET 0.
Cutting emissions by 100% and being net zero are two different things. Emitting a bunch of GHG and then buying carbon offsets is radically different from never actually emitting GHG. And the parent never says "net", it says cut emissions 100%. You're reading words that aren't there.
If you wanted to cut emissions 100%, you would stop making cars. You would stop making busses. You would stop building roads. You would stop building trains. You would ground every plane. You would stop every boat. You would no longer have AC, you would no longer have refrigerators.
Fossil fuels aren't 100% of GHG emissions. It's a large percentage, yes, but not 100%. So sure, you've cut 90% or whatever, but not 100%. You're still probably using virgin plastics somewhere, still making concrete, still making asphalt, still making steel, still need refrigerants, etc.
I don't think most people would want to live in the world where you've cut emissions by 100%.
Even making a bicycle emits some amount of emissions. Making a PV panel emits GHG emissions. Having a pet emits GHG emissions.