Why are we still using plastic drinking straws?

I got some takeout from one of the city’s finest restaurants this past weekend, and was discouraged to find two plastic drinking straws in the bag.
I’d ordered only one drink with my McDouble, so why two straws?
It was a mistake, clearly. But maybe the real question should be “why any straws at all?”
The straw issue is one of those things that humanity will look back on and scratch its head over. “You actually had plastic straws that you used just once and threw out