Managing people isn't rocket science, but some people are much better than others, with dramatic effects on productivity in both directions.
Yes, there are too many chiefs in many organisations (it has been said that there are more admirals than ships in the Royal Navy), but promotions and pay differentials are popular and efficient incentives.
A maximum 100% differential between the top and the bottom seems reasonable as a guide, but I'm not sure I'd like to see it in legislation: once you start where do you stop, and an industry would grow based on advising the unscrupulous how to get round it. And nowadays Chiefs often work longer hours than Indians.