1) We need a different term for the "post-money valuation" that VCs place on a company after fundraising. It is not a valuation in the same way that a public company is valued, due in large part to the preferred stock liquidation preference. Employees hear about a $1B valuation and assume that the IPO or acquisition price will be some multiple of that "valuation".
2) We need some tax reform that prevents employees from needing to pay a tax bill with cash for illiquid shares in a privately held company. It makes perfect sense for an employee of a publicly traded company to need to allocate some of their stock grants to tax obligations, seeing as though they can sell those shares at any time. But employees of privately held companies can't sell their stock (usually), and needing to take real dollars to pay a tax bill on those shares is just not the spirit of the law.