The driver got $5 from Lyft for the referral...if, in fact, they ever collect it, lol!
BTW, be sure to double-check your receipt from Lyft to see if you actually got the promised credit. Promises and reality are often different, especially with Lyft. (Also, the new-rider promotion is often $20, redeemable $5 per ride for the first 4 rides in that market.)
If Uber finds out about the referral, the driver will get deactivated. Both companies consider referrals to competitors unprofessional conduct and will fire the driver.
That said, I always suggest having both apps on your phone and check both to see if there are significant savings. That's especially important at peak periods when there is surge pricing in effect because they don't necessarily surge together or in the same amount. Sometimes one will be less expensive; sometimes one will have a quick pickup and the other company's driver may be some distance away. Be a smart consumer.
Also, now that you have accounts with both companies, YOU also have referral codes. If you have a friend thinking about using rideshare, send them your referral code. They will get a "deal" and you will get some kind of reward.