Their revenue last year was 136 billions. Even if we charitable assume app developers spend 10 billions per annum in aggregate, that's only 10%. Ancillary revenue.
Android alone accounted for $31b revenue in 2016, according to Oracle, of which $22b was purportedly profit just for 2016. Excluding Android's contribution to their advertising ecosystem, which is another chunk of that $136 billion you mention. That's far more than 10% of their gross profit, but even if it was less why would that absolve Google of responsibility? The % doesn't create the customer the transactions do.
It's probably wrong, just something internal Oracle leaked on a topic without much transparency. But even if all Google ever made was the $25 one-time fee all Play Store developers have paid they meet the criteria to be customers.
It's got to be about 2 decades since only advertisers gave Google money in exchange for goods and services, since then there are dozens of ways to be their customer.
Their revenue last year was 136 billions. Even if we charitable assume app developers spend 10 billions per annum in aggregate, that's only 10%. Ancillary revenue.