Apparently, the people in movies and television have really bad hearing, peripheral vision, and awareness of their surroundings. That's why they get hit by buses at random.
You've seen the trope on countless films and shows — a character steps into the middle of a street, often yelling at a main character or threatening to expose some huge secret — and then BAM! A bus careens into them from out of nowhere. Problem solved. It's like vehicular Deus Ex Machina.
This supercut shows just how often this plot device is used, sometimes seriously, sometimes hilariously, and sometimes rather stupidly. There's even a few surprise car crashes thrown in for good measure too. (Kudos to the editor for featuring one of my favorites, Life on Mars, including the great BBC original and the shitty American remake.)
If nothing else, it's a great way to spend 12 minutes of your day, and it's a good reminder of why you should look both ways before crossing the street.