There's just an irritating trend of calling guns what they're not.
The M&P Shield has a "single-stack" magazine. Glocks have "double-action" triggers - along with Kahrs, etc., etc., etc. But it just ain't so.
I've known for a long time that there are striker-fired pistols that are labeled as "double action" (or not), but there is a major problem with that - along with many hammer fired guns. But I just can't overlook the Smith & Wesson Military & Police Shield's magazine. Look at it!
It's really a 1-1/2-stack magazine. You can definitely see it, when you load the magazine.
That's irritating, but in the end it is only about hair splitting. But "double"-action triggers? I like second-striker capability, and there is a plethora of guns out there that are marketed as "double action" that are not real double-action guns. They might have partially-cocked strikers, or a partially-cocked hammer, but that's one-and-a-half action - not double.
There are a few that bridge the gap and give you second-strike capability - like some Tauruses - but the majority are frauds, with help from the gun press and the U.S. government.