I'd like to see some data to support your stance that Glock and H&K have great quality control compared to S&W. How many Glocks and H&Ks have you bought? But you "know what to expect"? How many Glocks and H&Ks are produced compared to S&W?
I've bought 6 or 7 Glocks in the past 15 years, most ordered sight unseen. Four HK's, 3 USP's, one HK45, all ordered by my dealer. If you include friend's pistols that I have first hand experience with, the number would be around 20. Never a bad part.
I think part of that is the way they are built, they don't require the same hand fitting that a revolver does. Also the hammer forged barrels and the molded frames tend to be more uniform. The individual parts are just thrown together, so it's easier to cull bad parts during assembly or inspection.
I think we've all seen the picture of the recent S&W's with bad muzzle crowns, bad forcing crowns, thread chokes, etc... Go down to your LGS and take a good, hard, unbiased look at the Smiths. My 63 had to have the barrel replaced it was so bad (rough), the replacement wasn't much better. I even had trouble with a custom shop 952. The sear broke twice within a month. They were very good about fixing it though. The 686 SSR that I saw at my LGS should have never left the factory. Even you would have agreed had you seen it.
I would never order a S&W sight unseen, and I'll stand by that.
Ruger, well my opinion of them has come around. I did order my flat top Bisley .44 from a distributer and was pleased. The GP100 looked great, so I put my money down on that. I may look for either an SP101 or 3" fixed sight GP and I'll probably have to order that.
With S&W, you do know what to expect. Ruger as well. Think about the amount of guns they put out...Every think that maybe they make more guns than the other "higher quality" guys, so then you see more problem guns BUT the actual rate is still the same? Simple logic, anyone?
IIRC, Glock pistols outsell S&W revolvers by a wide margin, and they have fewer reported problems with quality, so simple logic tells me they do better than S&W with QC.
Not a fan or recent Glock designs, but that's not really a QC issue.