The poll tax for one. Then when it was abolished through public outcry, adding VAT to household fuel - ie gas. Both of which hit the poor far more than the rich. And of course the 'rich' love to try and control the income of the poor to keep them poor. 'Twas ever thus...
Why? If you have an even rate of income tax, those who have little or no money left over after paying for basics pay proportionally more.
She certainly brought about some much needed reforms. But let's leave it at that. ;-)