[jtriangle]

Because if someone needs to open the door and the power's out, or the motor has failed, many people won't be able to do it.

That might be acceptable day-to-day, but, if opening the door is what's required to escape, say, a house fire, it's very much not acceptable.

[Red_Leaves_Flyy]

Should be a door or egress window in any garage.

[toast0]

Kind of hard to get a car out the door or window. Usually getting a car out of a garage isn't a big deal, because who actually puts their car in there? But also, you don't need to drive your car out if your structure is on fire ... OTOH, you may want to drive somewhere else if your power is out, especially if it's out for an extended period of time.