The use of UAVs for commercial use, including this application, is at present illegal in South Africa. So it's not at all certain that the client is a South African mining company.
You're oversimplifying the events at Marikana, which were somewhat more complex.
The shooting itself was preceded by days of violence in which striking miners armed themselves with pangas (machetes) and guns and massacred two police officers, two mine security officers and six other miners accused of not participating in the strike.
It was the South African Police Service, not the mine, which shot 34 miners on that horrible day. They did so after an operation to remove the miners from the hilltop went horribly wrong, causing armed miners to run towards a line of policemen who panicked and opened fire.
It also does not appear that the miners' union involved, AMCU, is negotiating in good faith. Their non-negotiable salary demand of approximately US$1170 in base pay plus another US$470 in benefits takes them into the upper percentile of all South Africans and is more than a software developer with a three-year degree earns on entering the workplace.
Moreover, each time the government and the mines reach an agreement with AMCU on wages, AMCU has added additional demands not previously mentioned. It's clear their main desire is to extend the strike, already the longest in South Africa's history and responsible for two successive quarterly declines in GDP this year.
Those types of wages aren't sustainable, so we're starting to see the mining companies adopt the same techniques used in Australia and elsewhere which are more automated and require far fewer workers.
In the end those who suffer will be the miners and their families, most of whom live in dirt-poor rural areas and have no other income options. They've been abused by the mining companies and their own union in equal measure and let down by an incompetent government. There's no good outcome for them now.