In reality though it isn't implemented as you described. In reality it is merely that there is a 62% marginal rate from 100k to 100k + 2x the personal allowance.

They do this with sole traders who face a £14k (~$20k) slab tax bill (VAT) if they go from £85k to £85,001 (~$100k). The outcome has been near total depletion of skill tradesman "mate" apprenticeships. Since such people (not being totally stupid) take 3 months off per year or work 4 days per week and turn down jobs.

it's very attractive to try and build a progressive tax system that swings too far the other way too. Economically some sort of tax free base and a flat rate is the best but politically it's way better to attack here and carve out these exemptions... the biggest winner is tax prep software.