Actually when I used the word "trust" I was thinking of countries with their own currency that have unstable governments and/or economies. So imagine country X exists in South America and you have 20 country X dollars. A week ago one country X dollar was worth 2 US dollars. But today country X decided to introduce into circulation hundreds of trillions of dollars in new currency to deal with their massive debts and it completely devalues your 20 country X dollars.

Or today there is a communist coup in country X and the new regime declares the old currency worthless.

That's what I meant by "trust."