In short, no, it’s illegal, and you will be caught. But, that said, there are legal ways to provide connectivity. It is also legal to put Wi-Fi across your own property but that changes if you cross a public space. You’re also not allowed to share your Internet link according to the contracts you sign for connectivity.
In South Africa’s wide open and expansive geography, the majority of people live in cities. But elsewhere access to services such as Internet can be problematic. Fixed wireless internet helps small towns, farmers, communities and rural residents get stable, fast internet.