What real life examples of security by obscurity have you seen/worked with? [closed]

Question

Bonus points for explaining how you improved it.

Answer 1

Real life security by obscurity?

The key to the front door is stashed under a rock nearby, or under the welcome mat, or on top of a high railing.

These are all instances of security through obscurity, as in, it is right out in the open for anyone to grab, but most people wont be able to find it without huge amounts of searching. However, a dedicated attacker can walk right in.