Originally Posted by Milton Keynes

Not to mention the sound of the engine running? I don't care how quiet a car is, you should still be able to hear it running after you get out. I guarantee that everyone except those with hearing problems ought to be able to hear a car running when it's sitting right in front of them.

I suspect it's more "dumbing down" and driver desensitization. We've got our noses in our phones and aren't paying attention to what we're doing, so it's easy for people to forget to turn their car off before shutting the garage door and going into the house. They've made cars with way too much automatic stuff in them to where people are getting desensitized toward driving.