The reason for the opacity is obvious, they want you to think the equity is worth more than it is.
People constantly assume good faith in these things when they shouldn’t.
Obviously number of outstanding shares is a bare minimum, but things like cash reserves and cash flow should also be shared but they don’t want to share that information, often times because it’s not good, they just wasn’t people who believe in the “mission” or that it’s a rocketship or whatever.
The secondary reason is that there are still too many naive engineers who assume good faith, drink the startup koolaid, and take these offers . Sometimes even declining public RSU grants to do so. One company out of ten thousand have ISOs that are worth anything but those are the only company in the headlines so the mystique continues.
The only solution is education. ISO (Incentive Stock Options) are one of the biggest scams of all time and you’re financially illiterate if you value them more than zero. They are carefully designed by venture capitalists to screw employees. NFTs of monkey pictures are infinitely stronger financial assets than startup ISO - I mean, as least the monkey jpegs have liquidity and volume, and no liquidation preference coded in to screw you over.