Edit: I guess you're probably talking about entering another country's border. I guess portability makes more sense there in that you don't have anything physical.
That said, you'd have to do all the conversion of BTC to fiat through shady channels, as by now all of the legal / above ground exchanges report every transfer to the local and international tax offices. Second, any conversion will charge a percentage.
In theory, BTC travels freely across borders without import taxes. In practice, it's useless if not converted to fiat, and all conversions are logged and taxed.
And if you want to force Afghan refugees (for example) to return and pay their taxes to the Taliban, then I don't know how to respond to that.
Bitcoin gives people freedom, as you can read more about here: https://hrf.org/hrf-op-ed-why-central-bank-digital-currencie...
edit: Post above originally said "One country's crime is another country's freedom" instead.
This is such an absurd straw man.
I really should look more into this Bitcoins money thing...