That term comes from EPA regulations about emissions, and led the entire aftermarket industry to figure if they put that on their parts, all was good. (The application here, applied to DOT lighting regulation, is likely bleed over)
A few years ago the EPA clarified that when they said “off road use only”, they meant in machines that were never intended to be on a road. So, aftermarket shit designed for a lawnmower, cool. But if you’re designing for a vehicle that was originally designed for the road, you have to stick to EPA regs. This killed a lot of those “off-road use only” disclaimers, but it also panicked the amateur racing community because they tend to use modified road cars. I’m not sure how they worked it out with the EPA, but I don’t hear them complaining any more, so I assume they did.
They are all "for offroad use only", which is the biggest scam