To use a simpler example: you flip a coin. Despite their being a 50-50 chance of it being heads or tails each time (this is the "program") you might, after 100, 1000, 5000 flips get results like:
heads 55 tails 45, heads 560, tails 440, heads 2800, tails 2200. After a billion flips you might end up with exactly 500 million heads and the same tails. But flip the coin one more time and you no longer have it 50-50.
True, the standard deviations should gradually, asymptotically grow smaller with large numbers of coin flips, but even with even numbers of flips there is rarely going to be exactly 50-50 results.
In economics, supply and demand may actually, in the real world, be in equilibrium for like 15 minutes once every few years, or millennia, but they will deviate from each other with the very next purchase, logistical tardiness (we should have those on Thursday) etc. Marx, in Capital vol. 3 shows that the same is true of value and prices - they MAY actually coincide every once in a while in the real world, but that is rare and almost coincidental.
This explains why every time I like a TV series it gets cancelled within a season or so.