How to work around the issue that I can't access some iStore apps of a different country? My family is spread across the world and I live and work in a different country than my native one. 

My iPhone and Apple ID are registered to my country of residence.

On a few occasions, recently, I tried buying apps that were available only in my home country (I don't know exactly why) - but I got an error message saying I couldn't buy apps in that country with my current Apple ID.

First, I am not entirely sure I understand the rationale for such a restriction. Is it some kind of trade embargo?

Anyway, the main question is what can I do to circumvent this pointless restriction and still buy apps that are present only in my home country?

P.S.: I saw there were a few similar questions, but I am addressing specifically the ability to buy/download the app and not just view it (I can already view it!).
You can make an separate AppleID for the other country.  You can load things from multiple AppleID accounts onto your phone at the same time, but it can be a bit of a pain as it will leave you in the account you were last in and you may inadvertently get new items into a different account than you intended.  Updating can be a pain, as it will require you to switch back and forth.  

But, you will be able to get the apps (or other items) that are only available in the other country.