For a commercial truck it isn't a big deal, the cable that you plug into the vehicle can be high voltage, and you can step it down right at the battery.
It doesn't have to be safe for idiots to handle, the rules are different for business users and employees. You don't need a professional driver or mechanic, the difference is in the liability and insurance rules. With the general public, you have to protect them from coming into contact with the high voltage, with business users you just need proper warnings, and some limited training about "if you touch the thing while it is turned on, you'll really die, follow the warnings."
For big trucks, you'll probably having something like a lug nut that tightens the connection.