[ipince]

> Unfortunately, most employees don't have the cash to do so.

I don't think using cash to pay the taxes is even an option.

> If/When they choose to sell their shares later on they must then pay a capital gains tax on the difference between the vest and sell price, effectively double-taxing them on the difference.

Why are they "double-taxed"? After the withholding, you get shares with a cost basis of X (the price of the share at the liquidity event). Any future capital gain/loss is based on that cost basis. Where is the double taxation coming from?