From my point of view, these vesting schemes all seem to assume the employee is a dishonest actor and to place a huge discount against the fact that the employe

From my point of view, these vesting schemes all seem to assume the employee is a dishonest actor and to place a huge discount against the fact that the employee is risking much more than a typical big-corp employee, for a much smaller chance at a very thin sliver of what amounts to a lottery-ticket-probability acquisition/IPO. A more equitable scheme would require a company to provide cash compensation "back pay"/"bonus" that brings the employee's compensation up to his would-have-been-market rate if the company terminates the relationship prior to the initial vesting. This protects the company and the employee: the company's shares are safe and the employee has a slight cushion in the form of a lump sum payment if he's cliffed.