2008 GMC Yukon latches & locks problems

First owner of a 2009 GMC yukon has had 3 door lock failures, which not only qualifies under the lemon law, but also poses a major safety issue. The first door lock failed. GMC does not consider door locks as a warranty item or safety item so I was forced to pay for a replacement. The next week, another door lock failed. The dealer did not charge for the replacement. Now, a third door lock failed only 10 days after the last repair. Why is this a safety concern?

Rear driver side door lock will only open manually. The key fob and electronic mechanisms to unlock this door no longer work. The rear passenger door now operates in the same manner (it doesn't). I see a significant number of people encountering the same problem.