Do you know how numbers on street lamp poles can help you?
Imagine you're on a walk in a park or in some place where you have trouble orienting yourself.
You see that something is burning or someone feels bad. In short, you need help. You call emergency services. How do you describe where you are when you have no idea what street it is?
Just in such cases, numbers on public lighting poles can help you. Those numbers are unique and operators can recognize where you are based on them.
And it works not only in Prague. Educate your friends :)