I have no emperical evidence other than I seem to see less issues on United these days with regards to unruly passengers. SWA and American are holding back on alcohol in coach and I wonder if that is causing passengers to belly up to the bar prior to their flight (since they won't be getting on the plane). Then come flight time, you have issues.

Now I'm not sure if just United has resumed alcohol on flights or others have - but I'm wondering if there is a correllation between airlines NOT serving and arlines serving?