This gospel goes against our sense of fairness. The same wages are given to all regardless of work. Whether for one hour of work, or the whole day, everyone receives the same pay. How is that fair? Yet the first hired agreed to this at the start. Take the job, get paid the usual daily wage. The rest were told they would be paid whatever is just. Or, they were not told at all exactly what they would be paid. But they all agreed, and they all worked.
Yet I can understand the anger of the workers who had worked all day long. They could have sat around and waited. But they needed the job, and they answered the call of the owner of the vineyard for workers. They were not cheated. What they resent is the generosity of the landowner. This is a story about God. The God we follow is more generous to us than we deserve. But when we see that generosity of God in the lives of others, we too can be resentful. We can decide to grumble. Yet when we truly appreciate the generosity of God, it is then we can rejoice every time God is generous, be it to us or others.