City bus and tram collide in downtown Belgrade

Probably because both drivers were simultaneously chatting or texting on their phones. They were temporarily distracted, as you would be.
It is not their fault. There are laws that prohibit this but these laws do not apply to bus and tram drivers (and police people). These laws only apply to "ordinary" citizens who, by the way, also don't give a flying f%ck.
There should be rule that only blind drivers can use a phone because to ban ALL drivers, well...that would be asking tooo much!

Probably because both drivers were simultaneously chatting or texting on their phones. They were temporarily distracted, as you would be.
It is not their fault. There are laws that prohibit this but these laws do not apply to bus and tram drivers (and police people). These laws only apply to "ordinary" citizens who, by the way, also don't give a flying f%ck.
There should be rule that only blind drivers can use a phone because to ban ALL drivers, well...that would be asking tooo much!