overpay them thus forcing up Polish wages and making the services inefficient for the customer.
Yes, you are missing the point. They are not overpaying them, but underpaying them, thus driving Polish wages down. These jobs don't pay enough to be attractive to local Poles with equivalent experience, who take better jobs or, often enough, go to work in the West. If they were not so easily replaced by Indians and Pakistanis, this would force Polish wages up. The influx of cheap labor from outside the EU keeps wages depressed.
The entire, and only, point of outsourcing is to keep labor costs as low as possible.