My first job growing up was a job at hungry jacks(Australia's burger king) I worked incredibly hard and got pushed to my limits many times, yet my wage wasn't that great and neither are most wages in fast food or hospitality. Now I'm currently working in logistics(Warehousing) and although my job comes with some risks associated with it such as possible injuries, my job is actually fairly easy and not that stressful compared to Hungry Jacks. I make more then double now working in logistics then I ever did at hungry jacks yet I feel working at hungry jacks was far more stressing mentally and physically.
One of the factors that made working at Hungry Jacks stressful was I worked at one of the busiest stores in my city, which made me realise it's unfair to treat all Hungry Jacks employees equal when it comes to wages, some stores are far more busy then others thus in my opinion I think employees should receive bonus's based on how busy the store is.
The fast food industry makes so much money, more than enough to pay their workers more or even just have bonuses like you suggested, but their goal is to always pay the lowest amount possible.
Sure that's the goal of any business as it is one way to maximize profit, but personally I feel that the fast food industry takes the cake for that.
I forgot to even mention the abuse and how many rules are broken by managers in my article. It honestly makes me upset that I never stuck up for myself or anyone else while working there.