Cars aren't secure. Most things aren't. The main thing that stops a theft is putting it in a place that's harder to get to (again, nothing is secure) just so that no one sees it, or has the opportunity to steal it.

I'm at a coffee shop right now, and my BMW motorcycle is parked right outside the window. Me keeping an eye on it is better security than any electronics lock system (as I know I could hotwire this bike in 30 seconds, and surely a criminal could too).