This reminds of an Iberia flight I took in early February. My seatmate pushed the call button to ask for a glass of water in the middle of the flight, a few hours after the meal service was completed. The flight attendant came by about 5 minutes later and without saying a word, turned off the call light, completely ignoring my seatmates request for the water.

I was too stunned at first, but then decide to press the call button on my side of the row and see what would happen. A different FA came by, and when I requested a glass of water, he told that they don't bring drinks to people and that I am welcome to go to the galley in the back of the plane and get it myself.

So it's not only UA, some airlines are worse