When you're at war you can't exactly bring power lines with you, nor do you want to be sitting there waiting ~10 minutes for the tank to fast charge while the enemy is shooting at you and you need that tank NOW.

Also apparently liquid fuels are extremely energy dense.

Logistics as I understand. Fuel is very difficult to replace from a transport/energy density perspective

Obviously, but if "let's not be evil" was a meaningful contributor we wouldn't be here