Is there any Uber discount for daily traveller?
The Guru Take
There have been in the past, but on a trial basis only.
There have been programs for frequent travelers, but they have all been localized or only on trial "invite only" basis.
Take a look at this article:
UPDATE - May 2018: Lyft announced an "All Access Pass" for a monthly subscription fee in major cities. There is currently a waitlist. Lyft's All-Access Pas. Monthly subscription coming to major cities. (invitation and waitlist only)