My only quibble is with the concept of "positive reinforcement" as if you were training a young child or a puppy. I think it's fine to say "thanks" or "I appreciated your taking Susie to school today," (assuming he didn't drive Susie while drunk). But "rewarding" the good behavior for the sake of rewarding it--as positive reinforcement, IOW, makes it a control tool rather than simply being pleasant.
People don't need to be REWARDED for doing what they should be doing anyway--adults don't, at any rate. The other piece of it is that they then use our failure to "reward" them as they think they DESERVE to be rewarded as another excuse for a resentment--another reason to drink or drug because "nobody appreciates me."
Just my take on it. Nice is one thing, "rewarding" is another.