Why do we Westerners think sending Manufacturing/Industrial work to third world countries is a good idea?

Why do we think that shutting down factories and dirty industries, then sending them overseas to places which exploit workers, almost non-existent Health& Safety, low environmental standards is such a great idea?

Wouldn't it be better if we kept them in countries which have unions and more environmentally conscious standards?

Why do we Westerners think sending Manufacturing/Industrial work to third world countries is a good idea?
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