The US should follow Canada's lead and not tax exercised options until the stock is sold and actually becomes income.
http://www.taxplanningguide.ca/tax-planning-guide/section-1-...
http://www.taxplanningguide.ca/tax-planning-guide/section-1-...
http://en.wikipedia.org/wiki/Phantom_stock
"Phantom stock grants and vesting agreements align employees' motives with owners' motives, i.e. increasing stock prices, while avoiding both taxable compensation and the need to give recipients voting or other rights typically associated with shares."
AMT helps the government get paid sooner than later for fast-growing companies. This mechanism doesn't have to affect non-C-level execs to be effective.
For non UK residents the first $16k of CGT in a year is not taxed.
Of course, it's very early stage companies that you really want options in...