Is there a reason to have coffee grounds at the bottom of an espresso?
Two possibilities:


It's just sloppy.  They're dispensing directly from the espresso machine into the cup, and as a result the finest particles that should be poured off, with proper technique, ended up in the cup.  Given that the main reason to dispense directly in the cup is that they're using a super-automatic (push-button) machine, I'd be pretty unhappy with that if I'd paid a lot for it.
They're deliberately leaving the fine particles in the pour to "prove" that it's real espresso and not a Nespresso capsule.  This seems misguided to me, but I can imagine someone doing it.