Lizard Drinking
I work as a pilot in a unionised airline in Europe.
It is our unions policy that we do not accept contract pilots unless there has been full consultation and agreement with our union reps.
The reason is nothing to do with dislike for expats.
Contract pilots are generally hired on a short term basis. They can be used by management to undermine a union. Any professional pilots association in a reputable airline with fixed contracts of permanent tenure and seniority system will always strive to have a fully permanent labour force...for the sake of the pilots in question as well as the union as a whole.
The figure of 30% contract pilots in Korean is shocking, and is far beyond anything our union would tolerate. So is 25%.
I sympathise with you if you've fallen foul of this philosophy, but it's a fact of life, and nothing personal.
As to safety. The safest airlineis one with a motivated and happy workforce.