The difference is once a company goes public then the have others to report to. Prior to the company being public anything can and should be allowed. Sucks but once you sell to the public you may be the majority owner but you still have others you must report to.
That maybe why it happens, but, it doesn't even close to justify it. Disney was public for awhile when Walt was in charge as well. One has nothing to do with the other. It has to do with compensation. For example, everything including the jobs of ALL of Walt's employee's hinged on the success of Snow White. Walt's very being was at risk, his reputation, his dreams, etc. The employee's only had their jobs on the line with no real responsibility for debt or anything other then a job that can be replaced easily. No, it was Walt (and Roy) that were taking all those risks. He had 100 times more to lose then the employees. He had to make the decisions that would affect not only himself, but, every single one of the employees.
Somehow that translates into "it isn't fair", he makes a lot more then us. He had a lot more invested then all of them. Why shouldn't there be a discrepancy, and a big one. I know if I built a business took all the risks, spent years in an up and down situation. One day doing well, the next eating out of cans, I would have felt that I earned that extra and would have taken it. I also believe that any of the people that say they wouldn't are just kidding themselves.
On the other end we have Iger. Nothing to lose other then reputation, Iger. A man who has enough money already to leave tomorrow with millions in the bank, no responsibility for the debt of the corporation. Never an original thought, never a risky venture that might blow up and cost him personally. Just a nice office, a big title and security for the rest of his life. He and others like him are just pure greed. Walt after the union, took actions to protect himself and his family. The exact same thing that anyone of us would have done in a similar situation.
Unless one has owned a business and built it from nothing, we can not have an opinion on how the owner operates it. If Walt hadn't known what he was doing, there would be no Disney Company today, seventy plus years later. He is a person that happens once in a hundred years. Many have talent, only a few can take that talent to its maximum and benefit millions in one form or the other. Walt's compensation should have been a thousand times over the others for what he created and the impact that his actions had on the world and all of us that were lucky enough to be here during some of the same years we were is priceless.