I flew UA twice and lost my baggage both times. They know where it is. A clerk told me so and said he had handled one bag. The Company told me that they would not send my bags to me or compensate me for them. In talking to others who have flown economy class on UA I have come to believe that a certain percentage of Economy Cass luggage is never loaded in a fuel saving measure. The staff on UA planes treat the passengers as merely an unreasonable requirement for them to do some desultory work on their vacation time. They don’t even seem to understand that it is the passengers that make it possible for them to wear the nifty uniforms and travel to exotic places which is what they think their whole employment is about. They resent the passengers and treat them with high disdain. I have also flown KAL and Cathay who treat passengers as if they would really like them to fly on their airplanes again. I never had any trouble with baggage or anything else on them at all.
It's worse! A certain percentage of Economy class passengers are never loaded in a fuel saving measure. They put up inflatable dummies in the seats so no one gets suspicious.