Why isn't there a sign forbidding breaking glass? This is a slogan to remind customers not to break the glass on the supermarket counter.

They can make it for you in the advertising shop, because few people have nothing to do to break the glass. Glass is stronger than you think. Generally, the glass of the counter can't be broken if you don't really hit it.

This is just like why there is no sign "Be careful to fall into the toilet" in the toilet, because it is unnecessary.