Yeah, compared to other European countries, prices in Poland are relatively cheaper (great places for a holiday btw ).It's in Poland. But I have to mention that all popular music services are offered here for similar price, including Spotify, Deezer, Apple Music and Tidal HiFi. Only Tidal HiFi Plus is twice more expensive.
Amazon, like other retailers, price according to where they sell, depending on exchange rates, the market etc. Remember when it comes to music, what they charge is largely dictated by the contracts they have with record companies, so it‘s not all Amazon.