Street smarts unlike wilderness survival, has a currency, both the financial and physical. Our gear.
I use non-local cash all the time. As souvenirs / backup cash, I tend to accumulate a healthy stack of various currency every few months, of which I exchange for local money when the pile gets to a certain size. Euros and US Dollars are especially powerful as “actual” currency in their respective foreign countries.
During an OP over a decade ago, I was in an undisclosed rural village in South America. My handler mistakenly couriered way too many Energizer AA batteries along with my equipment kit. I kept what I needed and gave the rest to a nearby bodega in exchange for 2 sandwiches a day for 2 weeks – not to mention cultivating a local asset.