If you shop at a butcher (or a grocery store with a real butcher) you should have them grind the beef for you. Pick out a piece of sirloin or chuck (or half chuck - half sirloin) and ask the butcher to put it through their grinder. This is the only way to make sure that the ground meat you’re buying is the meat that went into the grinder.
It can be more expensive than pre-packaged ground meat, but the latter can be a hazard (food poisoning and E. coli cases resulting from bad ground meat are so frequent). On top of that you’ll know that the meat has not been sitting on the shelf for days, which guarantees freshness. Ground meat is subject to the greatest amount of handling, which increases the risk of exposure to contamination. If instead you the process happens right in front of your eyes you’ll know that how many hands have touched it. Right?