Well for some people anyways. Pie isn’t particularly easy for me. After the flour explosion has been contained, liquids are sopped up from the counter, and I scrape off the dough stuck to my sock there may or may not be something edible coming out of the oven in 45 minutes time. So where did the phrase “Easy as Pie” come from anyhow? Well according to phrases.uk.org this particular phrase fits the equation of a very common type of phrase, the X as Y quotient. Easy as Pie, Nice as Pie, Sweet as Sugar, White as Snow, Quiet as Mice, etc…
To quote directly from the website: “The usage first comes in the phrase ‘as nice as pie’, as found here in 1855: ‘For nearly a week afterwards, the domestics observed significantly to each other, that Miss Isabella was as ‘nice as pie!’”
Mark Twain frequently used just ‘pie’ to mean pleasant or accommodating: In The Adventures of Huckleberry Finn, 1884 : “You’re always as polite as pie to them.”
“So he took him to his own house, and dressed him up clean and nice,… and was just old pie to him, so to speak.”
Pie was also used at that time for something that was easy to accomplish; for example, in The US magazine Sporting Life, May 1886: “As for stealing second and third, it’s like eating pie.”
And various other phrase-ology websites seem to agree with the above quotation.
So it seems to me that the staying power of this particular phrase comes directly from the Nice-ness factor inherent in Pie. You don’t have to be able to build a good pie in order to enjoy pie. Nor do you need to even own a pie pan to partake in the blissful feeling of eating that perfect slice of your favorite pie. Nostalgic memories of your (fill in your favorite relative)_______ (and now your favorite flavor)_________ pie are optional.