I'm fairly sure that at some stage it became illegal to transport people in this manner - but even with several recent tragedies related to this form of transport it remains common practice. I guess the reality is that for many small businesses it's completely impractical and too expensive to have a bakkie to transport goods and materials to a work site and a minibus to transport the workmen.
It's one of those difficult debates to have because I can assure you that if the workmen are faced with a choice to take transport like this, or find their own way to a work site, or lose their job, they'd jump onto the back of this truck in a flash.
The reality is that most people believe that an accident won't happen to them - so they're happy to take chances like this. Call me over-cautious or a wet blanket, but Russian roulette - it isn't my game. :)