"A contractor bringing in 50k gross and an FTE bringing in 50k gross have such disparate bottom lines, with the FTE paying several magnitudes the tax the contractor pays"
I call bull excrement!
A contractor (including his company, which is relevant to the overall calculations here) pulling in £50k gross taking his earnings as an efficient mix of dividends and salary will pay around £8k in corporation tax, then draw the remaining £42k. He will pay £2k income tax on this, for a total of £10k tax.
A PAYE employee will take home around £38k, so pay £12k tax.
How is this even close to "paying several magnitudes the tax the contractor pays"?!?!