Usually, if the flight is less than 45 mins in the air. Then, there is no service. I have never been turned down if I asked for water.

United has so many different regional carriers. Each carrier can have a different policy as to the flight time. Sure, they are a UX carrier. But Mesa may not serve on a flight less than 60 mins. Where as Go Jet's or Skywest would serve if the flight is 50 mins.

NOthing really that warrant's a complaint here.