Last weekend, I saw a group of boys in military uniform having lunch. The only information my level of Russian managed to get from them was that they we wearing the old imperial military uniform.
I now know that these cadets were set up in 1731. During the revolution, many cadets and graduate cadets fought for the White Russian forces against the Bolsheviks, so most were executed or deported. They survived in emigre communities overseas.
Some information is at this link:
Russian cadet corps
After the fall of communism, cadet corps were reformed in Russia.
The boys live in boarding accommodation (internats) and study academic subjects as well as military. To graduate as a cadet is regarded as an achievement and prestigious.
There is no cost to the family of a boy in cadets, but there is a selective entrance exam. Of course it isolates the boy from the family, but some parents like it in cases like both parents working, or single mothers, in order to give good training to boys.
For Australians, this sounds more like boarding schools (which are expensive), rather than military cadets, which are part time.