What Are These Called And What Purpose Do They Serve? [PICTURES]

What are these called and what purpose do they serve.  Take a look at these pictures...do you know why they exist?

Some business in Lafayette have this bumpy grating out front and of the ones I've seen, they have always been painted yellow.  Crossing this lumpy obstacle while pushing a basket was quite a challenge.

The one installed at Super One Foods could literally break eggs if crossed too fast.  I see that it's been removed.

Grating Removed In Front Of Super One Foods

Several days ago, I was pushing a basket full of breakables out of Hobby Lobby and almost broke the whole load because of the grating out front.  Take a look at it and decide if you've noticed it.  What is this called and what is it's purpose?

Grating In Front Of Hobby Lobby