Note: I believe that $2.6B figure that I found does not include the amount of ride revenue that goes to the drivers, so maybe that's why the valuation is so high. If you add back in the drivers share of the revenue, maybe the valuation isn't that crazy.
That number is quarterly revenue (and as you say does not include the share the driver takes)
A few years ago, if I'm not mistaken, they even switched to counting the entire value of an Uber Pool/Express Pool ride as net revenue (something they don't do with their core product offerings) muddying the water. Does anyone know if that's changed? [3]
$120B would price them at the same net revenue multiple as Square ($2.21B/yr @ 25B market cap) while Square has much, much better margins (0% vs -60%) - and is itself widely regarded as not being a cheap buy.
[1] https://techcrunch.com/2017/04/14/uber-shares-growing-financ...
[2] http://nymag.com/intelligencer/2018/12/will-uber-survive-the...
[3] https://www.bloomberg.com/news/articles/2017-04-14/embattled...