In your great–grandad’s day cars came with crank handles. If you had a flat battery, you simply slipped this handle into the front of the engine and turned it until the car started.
You don’t have this option on modern cars. Every car, from the smallest Daewoo to the mightiest Mercedes, is totally at the mercy of its battery, and yet batteries seem to get smaller and lighter with each generation. They usually work fine when the vehicle is new, but as the car ages, they grow old and die, sometimes stranding you at the side of the road.