You’re probably overthinking it. There’s always a risk of bags being deliberately or inadvertently taken from carousels. Many of these syndicates are mainly looking for quick cash, jewellery and perhaps some cards as a bonus. There’s all of our small amounts of cash and cards that add up, but there’s a lot of cash that gets moved across borders so it will be out of reach of their particular government. Thus carry on tends to be more of a target.
In Singapore I often change money over at Mustafa’s (24hr dept store) FX desk and always surprises me the wads and wads of cash people exchange.