This is a bit like people not masking for covid. Road safety depends on everyone having secure vehicles that follow all rules and that won't suffer power failures in the middle of the road. A bodged circuit that can pull that many amps can cause a fire, even if the truck is parked, and could cause a house, a field/forest or other cars to catch fire.

The worst part about it isn't just putting other people at risk, it's the dismissive attitude. "Oh, but it's my car, and it works for me" "why do you mind it so much if it's not your car" and "well, the rest of the wiring is even worse, so it's alright". OP should be worrying about their car a lot more, and you can have your car towed for this in many countries with tighter regulations.

While this bodge will work in a pinch, OP should really consider fixing it before using that car again, and they should definitely care a lot more about it and the possible consequences to other people.