You can accept tips as a driver, though there is no mechanism in the app to dispense tips (like Lyft does). When I went through my video “training” session in July, I was told as a bike courier I could not accept tips.
Sure, they make a lot of money by simply taking 20 percent off the top. But for certain jobs, they are not even making that 20 right now. That’s why I’m arguing their investment in the service is a ploy for the future, when they can jack rates and pay bikers even less (as they have done with drivers).