Learn English – You have gone through – you have been going through

The first implies that they, at some unknown past point in time, were exempted from paying tax, and they probably still are to this day (but not definitely).

The second, implies that right now, they are exempted from paying tax. It doesn't say anything about what happened in the past, or what was the situation before right now.

Your understanding of the three phrases is not quite correct:

1. has gone to - there or on his way to;
2. has been to - someone has been there but he is on his way back; OR someone has been there at some point in the past and is now elsewhere
3. has been in - someone is still there; someone has gone there at some point in the past and is still there

So these statements:

1. Have you ever been to / in Greece? - Yes, it's a very beautiful country;
2. When did you last go to Canada? - I've never been to Canada.

You could say HAVE you ever gone to Greece and it would be correct

I have never gone to Canada is also correct I have never been in Canada, while it would be understood, might sound odd to some. In this sentence I have never been TO Canada, would be correct.