Higher compensation level for Managers has little to do with negotiation skills. The real reason is that replacing average manager with good manager adds more

Higher compensation level for Managers has little to do with negotiation skills. The real reason is that replacing average manager with good manager adds more value to the company than replacing average programmer with good programmer. The reason for that difference is that good manager improves output of the whole team, while good programmer improves mostly single person output . In order to attract and keep good managers companies are willing to pay more.