THE groans were increasing.

They came from Candacy Taylor, a former waitress and current photographer of career waitresses, who was sitting next to me in a movie theater in San Francisco. We were watching “Waitress,” the new movie about three waitresses, many pies, romance and a pregnancy.

Having spent six years writing a book that became “Hey, Waitress! The USA From the Other Side of the Tray,” I felt obliged to see the film, but I was finding it to be, well, simplistic and cutesy.

The horrific murder last November of Adrienne Shelly, who wrote, directed and acted in “Waitress,” would make anyone predisposed to root for it. But as much as I wanted to like the movie, only the interaction among the waitresses was connecting with me. Candacy, meanwhile, had gone from groaning to scribbling notes.

As we blinked in the postmatinee sun, she exploded. Those girly, retro outfits! And no kitchen noise! Have you ever heard a quiet diner? And those trays. No diner waitress would carry one plate of food on a tray.

But the worst cinematic sin, to Candacy, was the overly made-up, smart-alecky, smoking, middle-aged waitress. That stereotype again.

No talk about sore feet, I ventured, getting into the conversational heat. And no apron stains. Not only that, but tips were barely mentioned.

Only later, though, did I realize what bothered me most.

Throughout years of interviewing waitresses around the country, from the revolving View at the Marriott Marquis in Manhattan to a suburban Philadelphia diner to a Zen-type haven in Los Angeles, I heard opinions from some 50 short- and long-term waitresses. (Why not waiters? I’m often asked. The nub of my answer is that they have it easier because they are men.)

Although the women I interviewed were of strikingly different backgrounds and attitudes, all of them, including some who proclaimed that they hated waitressing, said they were good at it. Few said they were good at everything about the work, but each one brought up a skill.

None used the word pride, as I recall. But they didn’t have to.

Some examples: I make sure my plates look good. I can “turn a frown into a smile.” I get along with the cook. I tally up my checks fast. My people don’t have to ask for refills. I upped tabs by offering a to-go box for the entree, so they would order dessert. I have lots of regulars. I could make a pyramid with water glasses and never spill a drop.

More examples: I know how to prioritize. I don’t let a customer eat something I wouldn’t eat myself. I can keep children under control. I could carry eight plates. I remember what everyone orders for breakfast. I always serve on the left and clear from the right, properly. I know when to give a free piece of cheesecake to smooth things over.

Some waitresses also said the following: “I can take it.”

That statement, I came to realize, encompassed not only pride, but also a paradox.

When I began researching “Hey, Waitress!,” I had two inklings. One was that waitresses, among the underheard icons of America, would have many important things to say about their work. That inkling proved true. The second inkling was that they might challenge a revered notion: that the United States of America is essentially classless.

Challenge the notion? They obliterated it.

“I had this guy the other day say to me, ‘Are you ready to take my order?’ Because is not your existence to serve and take orders?” recalled one waitress at a seafood restaurant in Kennebunkport, Me.

“What do you want? Eye contact?” an impatient man asked another waitress, who had offered to recite the specials and was waiting for his response. The scene took place at an excellent restaurant in Seattle.

Waitresses know that “taking it” includes a string of verbal and nonverbal slights: the “give me this, give me that” order, the “you’re only a waitress” show-off vocabulary, the “you are my servant for now” treatment, the noblesse oblige (or no oblige) power regarding a tip, the intrusion into one’s personal life, the twirling of an empty plate in the air until the waitress retrieves it (at Chez Panisse in Berkeley!), the returning of food, the lack of “hello” or “thanks.” (In “Waitress,” the diner’s owner and constant customer, played by Andy Griffith, is a curmudgeon, but with a heart of gold. Of course.)

Some waitresses told me that 50 percent of their customers were fine, 25 percent were great and 25 percent were awful.

The percentage of awful sounds awfully high, but consider what a waitress at the Tastee Diner in Bethesda, Md., said about a newspaper-reading regular. To signal that he wanted more coffee, he raised his arm (not his eyes) and pointed down to his cup. Finally, one day, she ignored him. Eventually, he looked up. At her. He got his refill.

THE paradox, then, is this: American waitresses take pride in doing work that they realize many people, including some they serve so diligently, put them down for doing at all.

And in the main, the waitresses of “Waitress,” though competent, did not (except for swooning over one waitress’s pie-making) indicate that they took pride in their work.

What Adrienne Shelly got exactly right, though, was her trio’s camaraderie. They knew, or learned, virtually everything about one another, cared about one another and helped one another.

Indeed, because of the work-pride paradox, it is no wonder that a bond develops in most restaurants among servers, male or female. Real waitresses need one another on the job, but they also need one another’s implicit understanding of it. They wouldn’t mind an extra serving of respect from customers, or from managers, either.

Now, that’s a happy ending.