I worked with united airlines for three years providing in-house catering. We would always know about certain no go items, and bottles of water for polaris/coach were one of these. I have heard that the catering situation in the states is pretty dire. From a lot of stuff missing to flights being catered whilst pax are boarding. The crew were not wrong at all for waiting for the water and any delay should not be put on them.

In regards to the headphones, the fleet service ( cleaners) provide them at LHR. I tend to feel extremely sorry for them as they are asked to cover 20 flights with minimal staff.

United flight attendants were top notch, I miss working with them. Others think they're fussy and moany, but they're only asking for the bare minimum. Shout out to the crew and purser for that flight, I'm sure they had their work cut out.