This is not true. Google pays better than pretty much everybody except for fintech and Facebook.
Likewise, I had an offer from Amazon around the same time as Google's offer - which was actually quite a bit higher. So from my own experience, and from friends, Amazon does indeed pay substantially more than Google.
I've heard other tech is sightly higher - however, I didn't go to Google for the pay (although I wouldn't say no to competitive pay, haha), but there were other drivers for me (work/life balance etc.).
Google is clearly in this too tier of companies that compensate well, but it seems to rely on its brand name to be a little stingy. Anecdotally though, a lot of Google engineers seem to work a lot less than people at these other companies, except maybe LinkedIn.
And of course it is significantly better paying then Amazon and Apple.
The stats are skewed by the fact that a lot of people who get L4/T4/E4 offers at other companies get downleveled to L3 by Google.
EDIT: It seems like Lyft, LinkedIn and Airbnb consistantly rank higher, I'm curious do they have similar perks though (free food for example)?
I'd say the general pattern is that Lyft and AirBnB are more selective in their hiring (which they can do with their smaller employee numbers), in exchange for paying more. There is also a risk premium since the value of their RSUs probably has more variability for companies that haven't IPO'd yet. And just a few years back it wasn't even clear when employees would get liquidity for their stock, though that has obviously changed now with the pending IPOs.
LinkedIn is an interesting case though. It's consistently the highest compensating company with liquid comp, and has a good reputation for work life balance. It's also not any more selective than Facebook or Google in hiring. I think being only a small division of Microsoft means it can be bankrolled and has less pressure to cut costs (I haven't seen any numbers for Github but it wouldn't surprise me if their comp is similar for the same reason). LinkedIn also likely compensates more to overcome the brand value / reputation that Facebook and especially Google have in comparison.
I should say though, having joined Facebook recently, that I'm noticing there are a ton of miscellaneous things that the company does to make employees' lives easier that may not have all that much monetary value, but really add up towards life quality. E.g. on-campus medical centers and insurance provider with really good customer service, e-waste dropoffs, and so on and so forth.
Also note that Pinterest probably didn't have enough data to make it onto the list, but it's up there with Lyft and AirBnB as a top paying decacorn - https://www.levels.fyi/?compare=Pinterest&track=Software%20E... Amongst public companies, Snap (https://www.levels.fyi/?compare=Snap&track=Software%20Engine...) is up there as is Cruise Automation (which doesn't have any data on levels.fyi but from what I've heard is also reasonably high paying).
It didn't happen for snap.
Otherwise, they're only profitable in some markets and have gotten regulated out of others. That leaves them with the options of scaling back or running at a loss. Neither if those confidently signal "value me higher than Costco or Adobe".
Uber already has more net revenue than Adobe. It has slightly negative profit margins but is growing significantly faster than Adobe, suggesting that there is plenty of room to let off the gas and let profitability take over at the expense of rapid growth.
In that light, it seems perfectly reasonable that it would IPO at a valuation similar to Adobe.