system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do Asian currencies tend to have very small denominations while western countries have big ones? For example, 1 USD ≈ 22,500 Vietnamese Dong

1 USD is about:

100 yen, 1000 won, 8000 kip, 35 baht, 22500 dong

But on the other hand, one USD is about

0.85 euros, 0.7 pounds Etc etc

So why is it that Asian countries have currencies that are so finely granular (for lack of a better term) that the smallest physical currency they have is worth 500 units? And why do western countries have currencies that are so big that a quarter of one unit is relatively significant?
gpt
Well, one reason is that many of these countries are ( or were ) quite poor.  So, poor people need to be able to sub-divide value quite small.

Another reason is relative inflation, many of these countries have had periods of really high inflation.  So the numbers have gotten really high.  As a comparison, the smallest coin (200 dong) in Vietnam is worth about 1 US cent.  

In fact, many countries will sometimes rebase the currency to get the numbers to be more usable.