There are more examples beyond this, but there may indeed be a trend emerging.
You also risk having cash stolen by border agents when crossing international borders. Many countries expect you to declare whether or not you are carrying more than a certain amount.
Examples:
Italy http://www.businessweek.com/magazine/italys-cap-on-cash-paym...
Spain http://www.bloomberg.com/news/2012-04-11/spain-to-limit-cash...
USA (Louisiana) http://www.klfy.com/story/15717759/second-hand-dealer-law
There are more examples beyond this, but there may indeed be a trend emerging.
You also risk having cash stolen by border agents when crossing international borders. Many countries expect you to declare whether or not you are carrying more than a certain amount.