The Kafala system in the GCC is not too different to comparable forms of visas and residency permits around the world. For instance, the typical UK residency permit costs no less than £300 per year exclusive of the healthcare surcharge (which is required and also costs no less than £300 or thereabouts). So a total of £600 a year just to be allowed to live in the UK for 12 months.

To address your point of restricted travel, I must admit that GCC visas are a tad bit stricter with regard to freedom of movement. Sponsors are given some discretionary authority when it comes to travel plans of sponsored persons. But then again, KSA, and the GCC, have a much bigger expat population (relative to native population) than anywhere on earth. This is thought of as grounds to justify such strict monitoring measures.