An Insight into Local Money

I've long been puzzled by so called 'local money' - notes that are bought with orthodox currency, but can only be used in a certain locality "Why Bother?" I used to wonder.

Enlightenment was provided by a discussion of Lake District money on today's television news. Tourists who buy the local currency often don't spend it all. Some apparently keep notes as souvenirs. Although that wasn't mentioned on the program, I suspect some don't notice they have unspent local currency until they've gone home where they can't spend it. Lake District Pounds issued now are valid only for this year, so any not spent this year will become valueless. The local notes that can never be spent represent profit for the organisation issuing them.

I thought there must be a catch of some sort. It's quite satisfying to have found it.