When I was living in England, there was a town in Northern London, called Kilburn, that had a very large Irish population, many of whom had come over to England to look for work. Every morning, young men would come to the town centre, and employers would drive up, select some of them for work and leave the rest.
Something similar would happen in Israel during the time of Jesus. Rising early each day, men would go to the city square to wait for someone to come by looking for workers. During times of planting and harvesting, there was plenty of work. Many a day passed, however, when no work was available, especially if you were not fit and strong and young. I am sure, many of those who heard Jesus’ parable in today’s gospel, were themselves common laborers who spent many a day in the town square waiting for employment.
At face value, this parable seems to be a good example of unjust labour practices with the early workers being locked into a contract at a far lower hourly wage than those who came later in the day. Each, regardless of how many hours they had worked, received the same wage. Those who hearing Jesus would have understood that entry into the eternal kingdom of heaven was the “wage” that all who were one with God at the end of their earthly life will receive through the grace of God. You can’t receive two or more gifts of eternal life. As with the man crucified on the cross next to Jesus (Luke 23:42-43), some may come under the grace of God in the final hours of their life while others may serve the Lord for their entire life.
“My thoughts are not your thoughts, my ways are not your ways,” says God in our first reading. The parable is not showing us a lack of “justice” on God’s part, but an abundance of His “mercy” instead. God will wait until the last possible moment to bring people into his eternal kingdom.