Earlier quoted context omitted.
"worth" being valuation based on debt. We don't know their worth because they aren't public.
It’s worth what people are willing to pay for it. In this latest transaction, people are willing to invest billions at a $48 billion valuation. This money isn’t even flowing to the company, but rather to individual shareholders. That means it is currently worth $48 billion.
Uber also wasn't worth $70B in the last round, investors didn't know that sexism was rampant and the culture horrible, which would have surely made them not invest if they had talked to female employees at uber.
However, they didn't know that the culture is horrible and not able to grow another 10x under these conditions and conquer the autonomous driving market.
They also didn't know that Uber had all these patent problem, but they did.
Now, investors have invested at a $48B valuation, but they still overpaid, because they don't know all the information. Maybe they didn't care, because Uber told them, they will definitely be able to bloat up the company to $100, so that SoftBank makes their 2x. Surely they also have liquidation preference.
So, they actual valuation of Uber, including all the bad that no one knows, is probably only at $10B.
It could also only be $1B, since Uber probably won't compete in the autonomous car market and can only make $50M profit per year after stripping away all its overhead. But most people don't know this.