Lyft embeds a tipping function in its app, while Uber does not. However Uber no longer advertises that tips are ‘included’ and allows drivers to solicit for tips. I’m not going to add the stress of cash, proper change, and the awkward friction at the end of a ride. Others take a different view.
I don’t like tipping but there’s no reason why it ought to be illegal — except to varying degrees it is in 13 states including Michigan, Pennsylvania and Virginia!