Two reasons the Asian car makers can make cars requiring less direct labor dollars. One is no UAW, the other is:

They use just in time (JIT) supply chain management processes. Just in time or the Toyota model is a supply chain management model where inventories are reduced to a minimum. This includes raw materials, supplies, parts and components. By reducing inventory, they are reducing costs including both carrying costs and labor.

The United Auto Workers is a labor union that includes employees of major american car manufacturers, but employees from foreign car manufacturers have continuously rejected any attempts to make them join UAW. This nto only includes Asian car makers, but also European car makers (e.g. BMW and MB).