The reason Apple's RAM is so expensive is because it undergoes very thorough RAM tests to verify it is 100%, and is also covered by AppleCare. So if your RAM goes bad, they'll replace it. Of course there is a large upsell $$$ here, but you're paying for stability. Some people just feel better going 100% Apple, despite the charge.
Of course, I never had an issue with RAM from OWC, so I always recommended it. I even helped a few customers purchase it in-store using the display units.
Totally fine.
Another cool story: You may or may not know, but new Mac computers used to (may still do) come with a $100 rebate towards a printer. The entry-level printer is exactly $100, so it is essentially free. There really is no catch here except you have to wait 4 to 6 weeks for the check to arrive. We (Apple store employees) knew that most people forget to file for their rebate, and manufacturers bank on this. So we were all officially trained to help file the rebate form in the store as part of the checkout process, to make sure the customer got it.
Also, even if the customer didn't want the printer, we'd usually try to sell it (for free, remember), and tell them to sell it on Craigslist, because they could get an easy $20 to $30. shrug Again, this was encouraged.
Isn't that second thing the case with OWC RAM too? That it's covered by some guarantee and that if it goes bad, they'll replace it?
I think the OP's point is that buying RAM through Apple (at a hefty premium) is a significant convenience for some people: if there's an issue - any issue - with the computer, take it back to Apple and they'll sort it out. Buying third-party RAM isn't quite as convenient.
Of course, in my experience Apple will happily look at your computer even with third-party RAM, but they obviously won't fix any issues caused by it.
http://www.macrumors.com/2012/01/17/apple-ends-100-printer-r...