I would be surprised if the audience for those vehicles want lots of modern updates, as well.
If I wanted those things, I would go buy a Highlander or other SUV-shaped car lacking the ability to go from pavement to AWD to 4WD to locked diffs if I get really crazy.
I like to call my off-road truck (rig in the vernacular) 'too dumb to hack'. Not that it has any meaningful security, but it is only electronic, there is not enough digital logic for there to be any attack surface worth exploiting, and even if there were some exploit, it cannot do much more than shut down the engine due to faulty timings.