I guess the main reason for painting planes is to create the image of the airline - branding etc. And the silver fuselage is now very tightly associated with AA. (And with air travel from a bygone age).

Same thing for putting airline logos onto the tableware and so on. I guess it could be cheaper if they all went for a boring, unbranded plastic knife and fork but they probably want to promote the brand. (Actually I remember an Aeroflot flight meal from the late 1980s where all the items were from different places - the butter was from Soviet railways, the knives and forks from a totally different Eastern European airline and so on and so forth).

I got to thinking about a really aggressive cost cutter - Ryanair. They're so tight-fisted that they're removing window blinds (reducing weight) and using non-reclining seats (reducing maintenance). I once flew a Ryanair flight from Dinard to Stansted in a plane that had been painted to look like a pint of Kilkenny beer. It felt slightly odd climbing into a pint of beer, but once on board it made no difference to me. I guess Ryanair made money from advertising the beer to offset their costs - all fine with me.

On the other hand, some budget airlines in Europe put their phone numbers or website addresses on the sides of the planes. That's some advertising for the airline itself. I don't suppose anyone has been able to measure the value of that advertising.