I would say inequality created by tax brackets is causing people who are acheivers to stay in the middle instead of moving up the ladder making it impossible for people on the bottom from moving up....
I have known people who ahve been ambitious who have been crushed by the fact that should they take a promotion they would earn less because it would boost them into a higher tax bracket and it would take 5 years worth of promotion before they ended up “breaking even” the effect this has on the people at the bottom who stay there because there is no forward flow is INCALCUABLE!
A "higher tax bracket" applies to MARGINAL not TOTAL income; a raise never means less after-tax income, although it may mean you keep a smaller percentage of the amount of your raise than of your pre-raise pay.