Hello Colin, welcome to cointalk! In my opinion the internet has made coin collecting a fairly global market, (which means more standardized pricing), but I have noticed sometimes US coins carry an even higher premium in other countries! I'm not quite sure why it is, other countries have beautiful designs on their currency as well, and I think as these other countries become more affluent we'll see prices on their old coins increase...... Like we have already seen with China. But, right now there's just more demand for US coins.
US Gold is recognized by Chinese gold buyers in all ASEAN nations as pure. That could also have something to do with the premium.
Well kinda, I think it's more of a trust, a confidence issue than anything else. This sort of thing goes back centuries, and not just with the US. At various periods in history different nations, countries, city states, have managed to capture the trust of the world in their currency. It started with Venice almost a thousand years ago, The Netherlands, Great Britain, and in recent history the US. People worldwide just develop a confidence over time that the currency, or in this case bullion coins, truly have the purity that they claim to have. That has often not been true with most nations of the world. So when 1 particular nation develops that trust and confidence then it's currency is given wider acceptance and often a premium over others.