It's true that small businesses and craftsmanship are not efficient, but that's not usually the main reason why houses are expensive. They are usually expensive because of planning controls. Look at the price of land: in places where houses are expensive, land with planning permission is by far the largest component of the cost of a house. Building work being expensive is usually a consequence of this.

Having said that, I've no idea where you live so it could be completely different in your area