OK, I see your point.
However, after having paid sometimes $400 for a plane ticket to podunk residency program in the middle of nowhere, sometimes paid for a hotel room and transportation to the interview, and show up and the interviewer doesn't seem to have read my application and we get the same food as the residents . . . Hello? I guess this is why some programs send thank you notes to applicants too, both sides put a lot of energy into it.
Some programs put a lot of time and expense into wining and dining residents, true. However, I felt that if I sent a thank you note to a residency program that I didn't like it would give the false impression that I would somehow rank them higher.
I guess I have been appropriately schooled as thank you notes would be/are nice. However, some attendings can be beyond abrasive to students, . . . after my first few clerkships I was like "Wow, most doctors have no manners and are creeps." Personally I like the graciousness of people who have manners, but these manners are beaten out of you in medical school. It does look old fashion and plain goofy to write a thank you letter to attendings for having the privilege of interviewing somewhere when they go cuss out of the next student in line.