From what I understand, it's not the airline that enforces the security measures, it's the airport and their security. And yes there are lapses all the time, not due to any evil intentions, I'm pretty sure, just poor training and low wages/poor working conditions. I have had mascara and chapsticks confiscated in Indonesia, and in Bangkok boarded with a full bottle of water that I forgot was in my bag, although I did have to give up the half full bottle in my other bag.

In China, I was behind a family that had several people carrying bottles of water or other drinks. The security people made them take a drink from each of them and then let them pass through with them. I was shocked, but I guess if the people are willing to drink it, how dangerous can it be?