well dunno what countery you from. but in the netherlands its diffrent(numbers made up)

person A 100k = 20% tax

person B 200k = 30% tax

person C 300k = 40% tax.

person A would pay 20% over 100k

person B would pay 30% over 200K and not 20% over 100k and then 30% over the other 100k

person C would pay 40% over 300k. and not 20% over the first 100k then 30% over another 100% and then 40% over another 100k