But people get more money as they progress even when then move into the higher tax bracket
Of course they do. But if the additional net pay isn't proportionate to the additional responsibilities, effort or hours, then many people will decide not to do it. Obviously. Particularly when they have other pressures in life, like children to care for and elderly parents to look after. And who does that normally fall on? Women.
I see it all the time at work. Men are facilitated in taking the longer-term view on this being progression. Women have to be more pragmatic about the fires they are fighting right now. So often - with monetary incentive largely removed by excessive tax - women will choose to "coast" and not go for promotions.
If we want a more equal society, removing excess tax burdens from people who are not wealthy so that there is incentive to continue to progress in careers is essential. Unfortunately often the stage of career advancement that coincides with getting to really fantastic jobs later is the stage at which 1) many women have young children; and 2) the tax bandings wreak havoc on the effort/ responsibilities: take home pay equation.
Uprating thresholds properly can largely remove this barrier. This would be good for individuals, particularly many women, particularly many lone parents! But also for the equality of society as a whole.
The current system has many distortions which discourage economic activity as I described above. Many posters have given personal anecdotes of it, also.
There is a reason that every Government in the last 20 years had proclaimed it will reform the tax system: it does not function how it should.
They all bottled it though because it's "too hard" (i.e. people would make the kinds of silly comments that are rampant on this thread). I hope somebody finally does it. It needs to be done. Annual uprating of thresholds at all levels should be enshrined in law.