I disagree, my email yesterday said "50% off your next 10 rides. You have 10 rides remaining. Max savings of $6 per ride. Discount applies to the fare, Prime Time charges, Service fee, tolls, and taxes only."
In the past two weeks I've been receiving offers for discounted rides from Lyft. First was 30% off for a week, then yesterday I received a code for 50% off this week. It seems they're trying to inflate their ride numbers quickly. I have not received any promotions prior to this, and I've been a member for over a year.