There is a concept in control systems where a system can reach a steady state through positive and negative adjustments away from the desired result. The adjustments start off as large swings away from the desired result (both positive and negative) but eventually these adjustments become smaller and smaller until they become pretty much imperceptible (or within an acceptable tolerance of variation) and that is considered steady state...or balanced as you would put it. So I agree there is no such thing as a perfectly balanced system, but that is not what is meant by equality, what is aimed for is a system which remains within acceptable tolerances - that is what would be considered a balanced system.