Why does the US have to pay so much for cash shop items compared to other countries?

[Toutatis]

I am very curious why the US has to pay so much for cash shop items in comparison to other countries.

For example, this newest outfit costs us $22 whereas in Euros it is 17.50€ and in GBP its £15.

Based on today's pricing:
If you convert 17.50€ into USD, it should be around $18.
If you convert £15 into USD, it should be $18.50ish
If you convert 2,420円 into USD, it should be $15.40 (tho I understand adding on a bit of tax to this one due to foreign conversions)
So how is the extra ~$5 being justified?
I know the cost of USD to other currencies is always fluctuating but I think accounting for a $5 margin is too much.

This happens with everything in the shop. Mounts, clothes, even our retainers cost more than it does for our European and GB friends. The differences between mounts is even worse in how much we get charged extra compared to our friends across the ocean.

Is there a workaround to this? Can I check out in another currency and just pay the small fee on my cc for a foreign transaction since I know it would be pennies and not a whole $5?

Ultimately, my main question is why this is like this and why US has to pay more in general and then the side question of if there is a way to work around it.

Guess what? Apart Brazil that gets local prices, it's even worse for other countries in the Americas that are subject to currency fluctuation. Other games I play let me pay in CAD. This game is becoming outrageously expensive at > $22 + taxes a month, especially considering how little new content there is. This is my last sub and I will not renew when it expires.