Second, the bogeyman of "letting some strange interloper see our books" is a myth. Every company's share plan that has share restrictions, also does not confer disclosure rights to common shareholders. That is, you have no right to see the books if you're a common shareholder in these companies. It's not the same with public equities as it is with this new round of startups. It used to be that case that you exercised 1 share of stock upon hitting your cliff. That way you could see the books and see what's really going on. The powers that be (Hello YC) have instructed their companies to remove disclosure rights as a workaround.
The myth that "having lots of shareholders increases costs too much" is also just a myth. Any company with a valuation north of a few mil can afford a finance team (or person) to keep track of registered shareholders. There are services that do this for you. We're talking about companies worth billions of dollars, not the corner bakery worried about the cost of flour because any rise might drive them out of business.