What's the reason of quality break in companies?

Applying quality assurance in a work environment if an added cost, so companies should select what quality criterias they can follow at each stage of their progress.Applying advanced quality assurance criterias in small companies may complicate the work environment at their stage, and might affect its finance.For large companies, this could be a result of not matching some standards, or not educate the employees about the standards, or not using the right equipment for quality assurance.