Again, spoilers if you haven't seen the film.
The end of the film sees the use of children to perform mortifying sacrificial tasks to keep the engine working, the train moving, and society alive. Without these children, the train would cease to function, but as they come from the back of the train, and the lowest station in society, they're seen as disposable.
There's been endless discussion about how this movie is an obvious analog for a class society where the rich have it good and the poor have it bad, so I'll just end by saying I can't help but feel world leaders and CEOs viewing working class citizens as the children in the train's engine: essential workers, but ultimately disposable.
If you feel like watching the end of the film again: https://www.youtube.com/watch?v=7gH-V3J2EuM