What I find curious about this, is that most people would feel short changed if their new vehicle did not come with a spare tire-even though that spare may never ever be used. Many of the same people see no need to hook up grounds "because they really aren't needed."
Yet, in most cases, if you need a spare tire and don't have one it is merely an inconvenience. However, if you need a ground and don't have one, it may well be fatal.
Some folks in other parts of the world have a different value for life safety.
We've been buying lights from China and consider them disposable after 2 years, and we're on a pretty good name basis with "Fong" in Los Angeles that actually takes care of importation. We had the wrong amber LEDs in one shipment, they sent us replacements and we had a local tech swap them, the importer gave us credit on our next order, and they came with the right LEDs.
If you're willing to buy 6 dozen of a model, they can customize certain features, like beam width.
We open every unit and check wiring harnesses and mechanical connections, and tighten all screws. Some units are perfect and others need a fair bit of love. While the importer makes good on things not right, we've found it prudent to order spares/extras at time of original purchase. Nudge, wink.