The unfortunate part is that many people that own the Chinese and low end Turkish guns actually believe that these low end guns are just as good as the higher end guns. They actually believe that the only difference is cosmetic, and some brag about having fired 250 or 500 or 1000 rounds out of their low end gun, not realizing that the service life of a higher end shotgun can be in excess of 100,000 rounds.
I wouldn't say most people think they are better or as high of quality when compared side by side. It's all about the intended use. For myself i am mostly hunting, crashing through thick brush, getting things scratched, muddy, worn. I don't hunt with dogs, and partridge in my area are very spooky and being in the middle of said thick stuff you tend to not get much for wing shots available. Typically you see them before they fly, or try to see where they land, and rabbits are usually stationary as well.
For
this intended purpose a short, inexpensive turkish gun will work just as well, if not better than an expensive, long barreled, very nicely detailed, made with superior materials and machines, high end gun that i have to constantly wave in and around alders.
No one expects a cheap turkish gun to last 300,000 rounds without any hiccups, but most people who buy them will never put that many rounds through all of their guns in a lifetime.
The OP never stated his intended use, or which brand is superior, or what anyone considers high end. He asked, simply "Looking for a break action side-by-side 12GA with short barrels (around 12.5" or so long) and preferably with a single trigger. Does such a thing exist?" and from the title was asking "What is the shortest but highest end double-barrel shotgun?"
To me, this means, of the available options, which one is highest end. It doesn't matter if italians make $60,000 over/unders if they aren't what the OP is looking for. If all there is available is a choice between chinese and turkish, for this type of gun, they are the
highest end.
So before everyone got into name calling, mud slinging and getting all worked up that people don't have the opinions that you do, how about all you guys who are experts answer the
original question? If you don't know of any guns that fit the OP's description, move on. If you don't like someone else's suggestion as they try to help, how does making fun of other people help the OP find what he is looking for? (and i'm not trying single you out or make any implications specifically stubble, your post was just the last one of a long list i don't care to read again that i could quickly quote to make my point.