Well, note that in my original comment I said "airlines" as in all airlines. Not just United. You can ask any flight attendant and more specifically any gate gate agent and they will all laugh and tell you that as a whole, the tone and tenor of complaints is inversely proportional to the price someone paid for a ticket. Its people buying the deep discount fares that cause the most commotion on airplanes. Hicks. People that use Kroger bags for luggage. So whatever. The number one thing is safety, and the industry does a damn good job. United has had some screw-ups. They killed a couple pets in years gone by, and this one is classic: (Even though he obviously lifted Merle Haggard's "The Fighting Side Of Me" to write it)
It is well known to international travelers that US airlines are the worst. The planes tend to be older, dirtier, with bad food and terrible entertainment options. Worse yet are the flight attendants who over the years have gone from attractive and smiling hostesses to old and overweight with a prison guard attitude. I get that passengers are also getting worse with entitled attitudes as well but more often then not, it's the flight attendants. Which is why I make it a point not to take US airlines if I don't have to. Luckily, being in Singapore, I've got one of the world's best airline at home.