Our society is much more careful about not spreading and catching germs than many other places in the world are.
For example, many of our public restrooms have toilets, faucets, and towels or dryers that don't have to be touched in order to work.
But when leaving those restrooms we must touch the doors, and if others who didn't wash their hands had touched them... well, you know.
And any public door that doesn't open automatically has probably been touched by someone with germs on their hands.
Playgrounds are often used by kids with colds, or coming down with other illnesses. That means any other child who touches the hand rails on a slide or the cords holding a swing is likely to be getting germs.
And how do we know library books weren't read by someone who was sick in bed?
The buttons on ATM machines or the ones in stores where we slide our cards were probably touched by someone with germs on their hands.
And..., and..., and...
If we try to avoid every possibility of being exposed to germs we'll have to wear space suits like the astronauts.
As long as there isn't a dangerous epidemic where we live, we wash our own hands before eating, and take the usual precautions, we probably don't need to worry about germs.
But (and here's the controversial part) immunizations do help keep us all safe, and it's only a myth that vaccines cause autism.