That's my assumption, that it's some legal dodge. Like "we didn't wire that light, so if you get in trouble for it, technically, you modded your Cybertruck, because we installed an inert lump of plastic and not an off-roading light. YOU installed an off-roading light." That sort of deal.
The strange thing, all the other manufacturers do ship pre-wired offroad lights. There's just something about the Cybertruck one that isn't up to regulatory standard, I'm thinking.