Several of the president’s friends — one of them a billionaire owner of a chain of grocery stores — said they cannot recall Mr. Trump ever doing his own grocery shopping. John A. Catsimatidis, the owner of Gristedes Foods, a chain of small grocery stores in Manhattan and Brooklyn, said in an interview that he has known the president for 40 years, but cannot recall a time when Mr. Trump entered one of his stores.

“I wouldn’t know,” Mr. Catsimatidis said. “I don’t have any pictures with him in Gristedes.”

Thomas J. Barrack Jr., another billionaire friend of the president’s, was blunt when asked if Mr. Trump ever did his own grocery shopping.

“No,” Mr. Barrack said in a text complete with a smiley face emoji. Mr. Barrack, a financier, did not respond to a follow-up question about how he got his own groceries.

Mr. Catsimatidis said that he knew Mr. Trump as a homebody who preferred to host associates in the comfort of a Trump Tower boardroom rather than go out to dinner. When he did dine out, Mr. Catsimatidis said, Mr. Trump was often in the company of one or two bodyguards, perhaps making him too conspicuous for the express lane at Whole Foods on 57th Street between Second and Third Avenues, four blocks from Trump Tower.

Mr. Trump has, at the very least, shown that he knows his way around a shopping cart. Last December, the president was photographed as he nudged a cart around a food distribution center in Utah, pointing at his bounty with a “can you believe this” look on his face and a grin before setting off through the facility.