It's also because there are pickers who make a living selling other peoples junk. I personally don't have a problem with it. Otherwise I'd sell it myself. But I don't. So go for it. This is why some councils have "book only" collection times. Instead of schedules. To stop pickers from going through everyone's junk.

I'd love to say it's just about insurance. But I suspect it's about money. More than anything.