You will find similar warnings, not "every 50 miles" but more like "50 miles after a wheel has been removed and replaced" in the manuals for medium duty trucks, and lighter trucks with dual wheels. You will find the precaution in the safety instructions packaged with almost all aftermarket alloy wheels. Dig deeply enough, you might find the same precaution in the owners manual for your car..
Call it lawyer's CYA, but it is because of a real problem, when first torqued a wheel might not be seated properly.
Dealers, tire shops, sometimes work around the problem on passenger cars by overtightening, which brings its own risks. Tire shop I use most for my cars, and alignment shop that takes care of wheels, tires, brakes on my RV, tell me "come back after 50-100 so we can check the torque on the lug nuts." Obviously, they treat it seriously. It is something I take care of myself, at least seasonally. Typically, 2-3 of the 32 lug nuts will tighten a little more when rechecked. None have been close to backing off.
Delivering used cars, from dealers to the shop where I worked, I have lost a wheel while moving. It taught me to check, and made me dislike wheel covers in principal. This is something that doesn't happen all at once, one or two nuts come off, additional load snaps the rest of the lugs. If you hear something rolling around inside a wheel cover, would be a good idea to check it out.