I'll admit I'm not up on the definitions. I'll go with you're definition. My thinking is geared more toward single stack v. double/staggered stack. More pistols sold these days are the later so I guess that's standard, just like 20 is standard for an M4.
Personally. I don't own any std capacity magazines anymore because of the changing laws in WA. They aren't illegal to own, but I can no longer buy those in this state. Nobody sells them anymore and it's illegal to import them. It's illegal to sell them in WA and might be illegal to sell anywhere but I get conflicting info about that.