>They give most of the profit to staff as bonuses. So, the bonus being quite high, the staff pay 40% income tax on it
Except they don't, the first 10K of gains is tax free and the rest is taxed as capital gains - that's why companies pay in stock options. There is also no NI paid on stock grants.
Here on the left pond, there is a lifetime $800K tax free for stock grant gains if your company jumps through the right hoops ;-)