Well, just because it's in Wikipedia doesn't mean it was written by a native speaker. I find dubious or sloppy English on Wikipedia all the time; in fact, I suspect language errors are more common there than factual errors.
If it is correct, it could just be something of a technical term, perhaps used more among puzzle manufacturers or collectors than ordinary people.
However, in a lifetime of doing jigsaws, I've never heard the word 'tab' used that I remember. It doesn't even sound very good to me, because a tab is usually square or rectangular, like on a file folder or a notebook divider.
In my family we've always called them stickouts, and the ones the other direction are stick-ins. I personally think of stickouts as more like heads than noses, and the flat part underneath is then more like shoulders, or wings.
Some people might occasionally call them outies and innies, which are very casual words used for types of navels (bellybuttons).
I think of the corner pieces between two stick-ins as spades, and the pointy ones between two stickouts as corners or points.
You could do a comparative search and see if any of those look more common, or perhaps others will comment.