Modern money laundering controls weren't possible until electronic money and record keeping, but then for related technical reasons it was much harder to evade the primitive controls they did have.
Gold was not the ubiquitous denominator of value: silver was widely used in ancient times. Generally empires needed coins to pay armies so gold and silver mines had strategic value.
In medieval times, this was the story in Christendom, although interestingly the Islamic world was associated with mints that did not adulterate their coins, which therefore kept their value outside the Islamic world and were much sought after in China.
You are right about the recency of passport enforcement.
I strongly recommend David Graeber's "Debt: The first 5000 years", which is an anthropological account of the changing role of debt and money around the world over history
I don't know about the legalities, but it may well be that banks have little choice but to comply versus going against the regulator. Though Barclays' line about "we want to protect your money" is a bit much.
What this bank does is trying to prevent crime before it may or may not happen.
This is sick and dystopian.
What's next, are we going to arrest people because they have cutlery and may or may not do something with it. That's preposterous!