The idea that a "minty fresh" mouth (or the idea that "mint" implies "fresh" at all) was the product of an ad campaign in the 1930s. It's not some sort of human universal.
But the association could just as well be to cinnamon, or spearmint, or blueberry. US toothpaste aisles have little variation, especially when compared to other countries without the mint obsession.
Then again the flavor choices in US potato chips is extremely constrained too. Never seen the notorious "hedgehog flavoured" in the US!
Practically any other flavor could be used, but mint in general - and peppermint in particular - "drowns out" other scents. So if your breath is just not-so-fresh, rather than downright vile, it's a better choice.
If you have to work around noxious smells, a bottle of peppermint oil gently daubed onto a bandanna or mask helps a lot.
