Yes most politicians use Teleprompters. However, few of them are so tongue tied when the thing breaks down.
Have you ever bothered to actually listen to the President when this happens? Most folks it does throw them for a second but they either turn to a printed copy of the speech or take a few seconds to gather themselves and then just wing it without thrashing about. It is as though he is two different people.
He's a pedantic perfectionist, when he knows it's going to be fed to him, he'll rely on it. Who wouldn't?
However, have you heard him in interviews and how incredibly composed, fluid and well phrased his thoughts are?
Now, have you given any thought to compare it to, ohhhh, let's say the last guy in office?