Think about this for a moment:
Do we really teach children – with the exception of the mine phase – what justice is? I mean, do we have to teach them about fairness?
With my own children, and the children I encounter is schools and other community functions, I hear adults and myself having to say “life’s not fair.” You hear that a great deal more of that speech than you hear people teaching young people that life ought to be fair, things ought to be divided equally, or people’s needs ought to be met.
We don’t teach youth justice, we teach them to endure injustice and inequality in and unfair world. Sometimes, without intending to, we teach them injustice, prejudice, and bigotry.
But the ideal of justice is apparent to us from a young age. The ideal exists in the human mind, even as our experiences as we grow older compound more and more reasons why it doesn’t, won’t, and can’t exist in our world.
That seems to reinforce the idea that the Kingdom of Heaven is a place where this ideal of justice must be realized. It also sheds some light on the fact that Jesus said we cannot enter the Kingdom unless we become like a little child.