Why don't they?
The same english crew that shut down the wrong engine could not see the flames and sparks coming from the engine. If they had they would almost certainly have got the right one.
WHY DON'T THEY FIT VIDEO CAMERAS, so the crew can see important parts of the aeroplane?
The Concorde pilots could not see the flames.
There are tiny video cameras available now. The crew should be able to look at the engines, tyres, brakes etc instead of wondering.
They could also look into the cabin for security purposes. If there were problems in the cabin, the video could be transmitted to ground security.