It's annoying to be bothered by the bad hygiene of others.
Whether they don't cover their mouth when they cough or they don't wash their hair/live in clean environment.
I think head lice CAN be dangerous, but am too lazy to research, got to love opinion.
Personal hygiene should be encouraged.
Why should this be something that is mandatory? Head lice cause nothing but an itchy scalp so it isnt anything that is a threatening issue. Kids these days will be bullied for head lice which is how many learn to have personal hygiene, if forced upon them, they may not want to have it - principle of being told what to do.