Lyft sends 1099(-K, presumably)s to drivers who make over $20k from 200+ transactions a year. This is the same reporting system used by Stripe and Paypal. (I have lots lying around.)

It would be exceptionally unwise to fail to report income which has been 1099-ed to you, and very unwise to fail to report substantial income merely because one does not have a corresponding 1099 for it, because (particularly in the case where one party has all the information required to reconstruct your income and that one party can simultaneously uncover millions of dollars of under-reporting) audits exist.