I've never had a company refuse to give me the 409a valuation if I asked point blank for it(just say you're considering exercising and it's important for tax planning). It's important to keep in mind though they tend to purposely depress that value. But investors get a premium because their stock has legitimately more value than yours(liquidation preferences, board seats, etc). And without a liquid market, if you do sell privately you end up taking a large discount. I think the opacity is largely that it's difficult to value things, not so much nefariousness