I need your help, please.
I want to sell in multiple countries with different currencies. The customer should always see their local currency, both on the product page and during checkout (where the customer can manually choose between locations and currencies at any time).
Now, there are a thousand apps out there that are supposed to convert currencies. But I wonder - why? Doesn’t Shopify handle all of that automatically?
I haven’t installed any apps so far, and Shopify seems to handle it automatically: In the front-end, for the customer, there’s a selector that allows them to choose between the different countries (the marketplaces that I have set up and activated).
If the customer switches the country - it will show all products and prices in the choosed currency, also the different product-price for this market-zone.
In the admin panel, I have set an individual product price for each marketplace (each of the countries I sell to). When the customer selects a country, the price is correctly changed and displayed (both on the product page and in the checkout). So, everything works, regardless of which payment system the customer chooses.
So why do I need an app that displays or converts different currencies for different countries?
Am I missing something or not understanding it properly?
Why do thousands of users use various apps for this?
And sorry if I might still be naive and ignorant. 
Thank you for your help and for your enlightening responses!