No, it's not mandatory. But it is customary for certain things, and if you intend to continue frequenting establishments or using services that don't entirely revolve around electronic payment you may find staff doing the bare minimum for you.
While I don't tip for stuff that's never customarily been a part of tipping in the past (barrista tip jars, tipping to have someone walk my meal out to the car, etc) I do tip for all the other customary stuff.
Good service should be rewarded…not taken for granted. And while there are those that will argue that good service is what employees are being paid for, no one seems willing to force change on the service industry so that employees are actually paid what their good service is worth.