According to adam smith and other classical economists, why is the economic theory supporting market economies(or capitalism) much more realistic than theories supporting sommand economies?

Classical economics is a branch of the economics that states that economy is always moving towards equilibrium, which means that a change in supply will eventually be matched by a change in demand. The father of classical economics  is Adam Smith with his book The Wealth of Nations in 1776.
The economic theory supporting market economies (or capitalism) is much more realistic than theories supporting command economiesIt is based on self interest.

Look it up you feel me

You would need to take a picture so i can see