Here's my guess: most of the B-truck drivers have the situation that when their hydraulics go, they need to fix it NOW. I'm not sure most have the luxury of a different vehicle to drive for a few days while they wait for shipping on such a part.
And most aren't going to buy this kind of a part to have in advance, to install at their "leisure", like a replacement fuel tank sender, because it's not a $5 part. That's just my opinion; stuff like fuel sender, temperature sender, brake pads, shock absorbers, ball joints, etc. are more like jobs to replace when schedule permits.
In my own case, I've been told by CarQuest that no more free replacements on my cylinders, I've been to that well too often. But I also have my 1971 VW to drive, or could pull back my Frontier from 100 miles away, if need be.