Taxes in Canada question

Okay so I'm doing a paper on taxes in Canada, and I just want some clarification.

Firstly, besides registered native Canadians, who are exempt, who else is exempt from taxes in Canada?

Secondly, there are obviously people who get away with paying minimal taxes. Who pays minimal taxes and receives much more money worth of benefits from government, that creates a net drain?

Anything would be helpful, thanks!

edit: I know natives are not entirely exempt, I was more just wondering if there are any other particular group of people that are also exempt from varying taxes.