To understand this we have to go in history.
In history Turkey is the only country which practiced azan in its native language (Turkish) but this was not adopted by other Muslims.
Detail from wikipedia
As an extension of the reforms brought about by the establishment of the Republic of Turkey in 1923, the Turkish government at the time, encouraged by Atatürk, introduced secularism to Turkey. The program involved implementing a Turkish adhan program as part of its goals, as opposed to the conventional Arabic call to prayer.
The adhan was replaced with the following:
Şüphesiz bilirim, bildiririm
Tanrı'dan başka yoktur tapacak.
Şüphesiz bilirim, bildiririm;
Tanrı'nın elçisidir Muhammed.
Haydin namaza, haydin felaha,
Namaz uykudan hayırlıdır.
Following the conclusion of said debates, the Presidency of Religious Affairs (Diyanet İşleri Başkanlığı) released an official mandate on July 18, 1932, announcing the decision to all the mosques across Turkey, and the practice was continued for a period of 18 years.
Because being a Muslim, we have to follow Arabic as the sacred language of Islam. In history people used other language instead of the sacred language and forgot the true massage of Allah due to translation.
Translation in another language can't be completely accurate. And by doing this, the sacred language may die. We know that the sacred language of bible has died due to not speaking.
That is why Harun al-Rashid took dramatic steps to secure Arabic and not to mix it with persian. So as a Muslim, it is our responsibly to learn Arabic. That it is not taught is wrong. As far as non-Muslims are concerned, they always try to find fault with Islam no matter what we do.