No, that's not how that works. The preferred share and common share prices converge towards a liquidity event, like an IPO, when preferred shares are converted to common shares.
It's expected that common shares are worth less than preferred shares. After all, the preferred shares could be paid out at value in, e.g. in the event that the company is sold for far less than the current valuation, and the common shares would be worthless.
It's a de facto standard because markets for common stock generally don't exist for private companies. If you're comparing Uber against AirBnb it makes sense to compare valuations based on preferred stock, if you're comparing them to anything in "the real economy" or are interested in the value someone has placed on the company as a whole it's less clear which number is more useful.
Agreed that the press does go around using this $70B number as a valuation. If the company IPO'd at less than $70B it would similarly be reported as a dud. Recruiters also use the $70B when offering stock options. And I'm sure it feels like a haircut to those employees who just sold their stock at a $49B valuation.
All of the employees who sold in this tender offer have options, which have a maximum strike of less than $20 per share for common stock. Only RSUs were issued after early 2015. Uber’s valuation was $40B then.
I've only got two IPOs under my belt, but both cases the 1st trade settled above the preferred price in the last round. I think that's fairly typical, fwiw.
Having the stock after IPO trade at the old preferred price represents a significant increase of the actual value of the company, even though it's not usually reported as such.
It's expected that common shares are worth less than preferred shares. After all, the preferred shares could be paid out at value in, e.g. in the event that the company is sold for far less than the current valuation, and the common shares would be worthless.