Because it's happened before. People were calling the iPhone a flop before it even released. People are calling the iWatch a flop, again before it even releases. Now they're doing basically the same thing with the Apple car.
And yet we've heard nothing from the automotive industry. No auto company has said a word.
Reality is that Apple will likely never produce a complete car. It's a bunch of assumptions based on speculation of what Apple might be planning.
A smart company could quietly create the impression that they're working on a car, and let everyone focus on speculation about a car, and then catch everyone off guard when they release an amazing new computerized refrigerator that acts as the central hub for your house and provides you with amazing interactive content.
An old business strategy is to get your competitors all thinking about something else, and then shock them when you go a totally different direction.
It could be very possible that Apple is working on an airplane or a space craft. Who knows. So they've hired people with battery tech and transportation and mechanical backgrounds. A guy who designs drivetrains could be useful in a number of mechanical engineering applications.
Everybody's speculating on circumstantial observations and rumors with no facts. And the mac fans are getting excited over a bunch of things that could mean nothing.
Maybe Apple's going to introduce addons for cars. Maybe they're going to integrate a Garmin type navigation system. Who knows.
Let the competitors make wrong assumptions, prepare to compete in the wrong areas, and then blow them out of the water when you release what you actually intended to release.
Perhaps more simply put... Slight of hand.
At this point, it could be anything. And it could come to nothing.
And, there's no conspiracy going on except in the wild imagination of a bunch of uninformed apple loyalists who thrive on believing everyone else is out to get them.