Well this is true for alot of companies not directly in video games industry per say. At my company for instance(nda) works with 2 outside QA companies. Witch hire peoples right at the bottom of the barrel witch had no experience in QA so most of the times we have visual faults going to our customers that fly right under QA due to inexperience or lack of interest. So yea its prety common as far as i worked at multiple companies and alot use external QA  than built in house and have higher standars...