In another telling anomaly of the meat-grinding business, many of the larger slaughterhouses will sell their product only to grinders who agree to not test their product for E. Coli contamination--until after it's run through a grinder with a whole bunch of other meat from other sources.. It's like demanding of a date that she have unprotected sex with four or five other guys immediately before sleeping with you--just so she can't point the finger directly at you should she later test positive for clap.
Food safety oversight is largely, but not exclusively, divided between two agencies, the FDA and the USDA. The USDA mostly oversees meat and poultry; the FDA mostly handles everything else, including pet food and animal feed. Although this division of responsibility means that the FDA is responsible for 80% of the food supply, it only gets 20% of the federal budget for this purpose. In contrast, the USDA gets 80% of the budget for 20% of the foods. This uneven distribution is the result of a little history and a lot of politics.