Airportable

I suspect the root of this is associated with the switching circuits. In our cars the switching is mechanical, where the positive is switched relative to ground (chassis), whereas in the Freelander the switching will be electronic.
Modern car electrics use MOS FETs to do the heavy lifting & there are two polarities, P channel & N channel.
To switch a positive line a p channel FET is used, conversely an N channel switches a negative line.
N FETs are easier to make & use plus they are so much more reliable than P, they also run cooler.
Old fashioned switch gear switched old fashioned current, i.e. amps, amps needed umpti contacts (costly), next to no current is required to switch electronically & a small amount of current is all that’s needed to turn a MOS FET on.
Conductive rubber will pass enough current to switch a FET.
Where ever practical I use FET switching in my designs. At the basic level, devices have a positive pole & a negative, (think torch) it is no more difficult to switch the negative than the positive, once over that hump & providing you have experimented with & blown several up, why buy a five pound switch when a simple touch switch & FET circuit will cost half that & you get twice the fun applying your new knowledge.
M