When I have leftovers at a restaurant, I ask, “Can you bring me a box, please?” so I can pack it myself, since waiters tend to dump it all in a heap of what looks like dog food when you open it the next day. This works only half the time. To the others I must politely explain that I’d like to pack it myself. Mostly they’re great about it, but occasionally I’m treated like a freak. Shouldn’t waitpersons be taught how to handle this?
With all the attention that fussy chefs and restaurateurs pay to proper plating these days—if Mr. Manners sees one more photograph of a chef bent low to make sure the bits of chive are placed just so as they breathe all over someone’s elegant plat du jour, he may just wretch into his work shirt pocket—you’d think the wait staff would pay equal attention to repackaging the remains of the day. But you’re correct, that $40 entrée usually looks like obscenely expensive hash by the morning after. So insist in good conscience, and adjust the tip as needed when your request is ignored.