It turns out, that knowing the chronological order of two events is kind of a useful thing.
If you sell cinema tickets and there are two buyers for one seat, you need to know who was first. You sell the ticket to this person and deny the other. If you have just one ticket office window, it's easy. The buyers form a queue and the order of ticket sales is thus determined. The thing with this approach is, it does not scale and if you want to fill a large cinema or you run a cinema multiplex you are in trouble. The queue would be too long.