Gold is one of the easiest things to smuggle: it is compact and can be easily melted, painted over, made to look like a cheap tourist souvenir, mixed with other components, etc. and then recovered at the destination.

That does not mean that it is trivial to smuggle gold out, but if you need to do so, the chance of success is pretty high. Much higher than smuggling out fiat money held in a government-regulated account during capital controls. My 2c.