How does voluntary trade promote economic progress?

Voluntary trade promote economic progress:

Voluntary trade promotes economic progress because it encourages businesses to seek lower per-unit costs by adopting mass production methods. In mass production the production cost of per piece of the it or object decreases gradually. This happens because the mass production is done with machines so the amount of wastage is reduced and the time consumed is also reduced.

Also machines produces products on large scale so the machine running cost is also settled down. When the raw material is purchased in bulk it also costs cheaper so the final price of per piece gradually decreases. This how the lower prices on the mass produced products attract customers in large numbers and increase the sale which promotes the economic progress.