I guess I'm a bit of a stingy old git, because I will always pick the free postage option unless I really need the product in a hurry. But what amazes me is just how slow some of the free postage services take sometimes: I've had things take up to two weeks sometimes, and I live within 50 miles of London, so I'm not on some remote scottish island that only gets a boat once a week.
What I don't understand is the economics for the supplier, who is usually Amazon. I understand it'll be cheaper to send items when there's spare capacity, and therefore the free postage will typically be delayed by a day or two. But surely at some point the costs of storage along the chain must start to outweigh the savings in waiting for spare capacity on a van or train?
Or is it also intended to push people towards paying more for postage, in which case do amazon et al. make money out of the P&P charges and therefore want to make things uncomfortable for tightwads like me?