Wiktionary
a. (context US simile English) Having characteristics considered quintessential to American life; very American.
Usage examples of "american as apple pie".
But even had they wanted more posies they'd have had to wait till white settlers brought a whole Noah's Ark of extra old country greenery such as alfalfa, chickory, clover, dandelions, and even that Kentucky bluegrass everybody thought as American as apple pie, which was Pennsylvania Dutch in the first place.
This link between sex and death, well, hell, it's as American as apple pie.
They laid a phony history on you that was as American as apple pie, or should I say Georgia peach pie, and seemingly as genuine as the Confederate flag.
He wants to make violence as American as apple pie because it excuses violence when it's used to promote something he believes in.