Apparently, Japan has one of the “cheapest” prices for the game while elsewhere it becomes a rip off for some reason (as referenced, in green: is converted from JPY while in red: is the price of the same thing in USA, Europe, UK, Australia, Brazil & Poland to name a few places).
The thing with pricing is that different countries have their own rules on taxes, so it’s kind of finicky to compare (as US has sales tax added upon checkout while EU includes VAT). The weird part is that both $ and € use the same numerical figures despite them being different currencies, as in 80€ is treated the same as $80 when the conversion does not match at all when you look it up.
I don’t think Steam doesn’t pay sales tax. It’s probably just included in the final amount.
Steam absolutely charges sale tax in addition to the base price in my area (I think my state passed a law some 10 years ago to capture lost tax revenue from online sales).