When they brought in the " no charge, contribution only" payment for literature here in Britain, I can't remember the year, even though I was Literature Servant at the time.
It was put across to the brothers/sisters "When you get your books or mags put a contribution in the box provided at the back of the hall."
Then this was followed up by a demonstration of placing the literature. Saying to householders "There's no charge, we just accept a contribution for them." Then you kept this money separate and put it in the box when you are next at Kingdom Hall.
Hold on! I thought isn't this paying twice for the same item. First from the brother when he picks the literature up then when householder gives him money for it, that also goes in the box.
I raised this point with the PO and Service overseer, who looked at me blankly, then it dawned on them. "Well thats the way the organisation wants to do it, so we do it that way." I said the brothers won't buy it.
Sure enough when I was taking payment for Literature (books, brochures etc) I could take about between £100-£200 a month. After the change we were lucky to get a £100 in a month. Brothers were even order things like De-luxe Bibles, Insight volumes, videos, etc. Of course they were at "no charge" and I'm damned sure the money never went into the box.