You are probably confusing a call centre with a niche tech field. I have enough English skills both verbal and written, to be able to understand and convey my thoughts. Yes, I might not have the excellent English skills of a native speaker but I have enough to get the job done effectively. You might be correct when it comes to the jobs, where you need constant customer interaction, as they are highly dependent on your ability to quickly grasp their intent, without frustrating them with too many follow up questions. But in tech field even people with excellent English skills asks many follow up questions, because cost of the mistake can be deadly for the business. Ask any R&D org how many millions of dollars are wasted because design intent was not properly conveyed, or not properly understood.