I doubt asian produced bikes dominate the market in the west. See eg http://www.conebi.eu/wp-content/uploads/2016/09/European-Bic... - 7M imported and 13M produced in 2015. The asian industry is also much younger so the "decades" is not really an advantage.
Most bikes in US and Western Europe are made in China. Then they get shipped in parts to US and Western Europe and the bikes are assembled there. Often enough such small tasks count to label it made in xy.
Only smaller volumn hand made premium bikes are made locally.
Also bikes get imported from low cost countries with cheap labor like East Europe and China since at least 1990.
