One company I worked for was known for being one of the lower cost vendors in its industry, and I experienced a pervasive back-stabbing culture, which I attributed to there being many employees who were especially fearful of losing the only job in the industry that they had been able to get. So I think in a lot of cases, the lower paying companies might have employees who are more desparate, and management who is used to having more-than-typical negotiating leverage, which they do exercise.