Why do boys not wear collars and ties nowadays?

In the 1940s/50s, it was part of a boy aged 8-18s usual clothing. Why do boys not wear ties anymore. I think that parents should be stricter on their sons. I know some cinema's are starting a 'all males must wear a tie' rule. I think that this is a good idea, because it will encourage young boys to wear ties. Boys should wear ties as an everyday item.