The samba school system seems to be unique to Brazil.[14] Unlike parades such as the Rose Parade in California, for instance, the samba schools’ organizations consist almost entirely of community volunteer work. More than just musical groups, the schools are the neighborhood associations that cover a variety of community needs, such as educational resources and medical care. There are often political and commercial interests involved as well, even from abroad, especially when the samba school honors the literature, music and dance, or a myth, historic figure or event from another country. Drug lords who control trafficking in the Rio favelas as well as illicit gambling (Jogo do Bicho) are also said to contribute financially to schools, as many of them are guardians and controllers of shanty town life.
Source: Samba school – Wikipedia
Tim B.
“Natural associations are almost always local, largely from poor communities or the suburbs, forming samba schools that usually represent in a district, sub-district or set of districts. A parade which usually has local character, whereas the main schools of the city gather to compete among themselves for the best of the year. In this show, conducted over two nights, they are evaluated by a committee of judges chosen in advance by their leaders or by the representative.[26][27][28]”
Tim B.
“The samba during the parade should not be interpreted by one or just a few people, but sung by the entire school: the music should only be “pulled” (initiated) by the minority group. Moreover, many believe that the handle would be a special category of performer, able not only to interpret a samba, but also encourage and arouse the audience. “
Tim B.
https://en.wikipedia.org/wiki/Bateria