>> I'm picturing going to a facility whose owner has put up a sign saying "Grocery", and asking for milk, and being told the grocer doesn't just load every imaginable good into his store so if I want milk, how come I haven't got a cow?

I'm picturing you going to a facility that offers free product goods from charity donations (such as the Good Will or Salvation Army, etc.) and you asking for a free modern home stereo system, and being explained that there are many items available for free but only things by people who donated - and then you replying that you would like the facility to go find someone to donate their stereo system so that you can have one for free.