Also, seen from the other side: They made a contract offering 40% in four years (conditionally) - most importantly only relevant when the company/idea survive that long and are thus profitable/worth something. Why should they suddenly pay this (or a meaningful fraction?) out after one year? Or give an "outsider" 40%, which will most certainly be difficult to explain to future investors?
a standard vesting schedules is 4 years with a one year cliff.
That means that after one year the person will have vested options worth 10% of the company. they will then accrue more options every month until they've fully vested their 40%.
That doesn't mean they'll only get 40% after 4 years.
And typically when you are terminated without cause a good vesting contract will foresee in that and trigger the 'accelerated vesting' portion of the contract. Ditto with an early sale and possibly other trigger conditions.
Also, seen from the other side: They made a contract offering 40% in four years (conditionally) - most importantly only relevant when the company/idea survive that long and are thus profitable/worth something. Why should they suddenly pay this (or a meaningful fraction?) out after one year? Or give an "outsider" 40%, which will most certainly be difficult to explain to future investors?