Where as with a hover-cab, before you get to theoreticaly use zoro-emission fuel, you first have to make it

This sounds almost like tractors are born in a shed, not made in a factory.

digging up and smelting rare metals

Not so much and less with newer battery types

shipping parts all over the world and churning them out in coal-burning factories.

Again, see first comment. Out of curiosity, what are coal-burning factories anyway?

You’ll be dead before your tractor catches up the starting costs.

While tractors are relatively cheap, you fail to see all the disadvantages with them it seems. Like fuel grows in a fuel pump stations and I'm sure they are very beneficial to air you breath, not counting co2 emissions and many other negative aspects. Let's do a test. I'll lie down next to e-vehicle exhaust and you'll do the same next to a tractor exhaust or any other ICE vehicle of your choice. Let's do that for 5 minutes while engines are running.