To be honest, lighting is a process, even in the real world. Look at a photographer's studio, he (or she) has screens, gels, back lights, bounces, key lights, fill lights, etc. The problem with most people who complain about things they don't understand is that they just want them to work, out of the box, perfectly, each and every time. Now, here's a little secret, by it's very nature, that's NOT art. In fact, if you did manage to eliminate the uncertainty factor then you eliminated the art itself.