Okay a 5 year old should not be handcuffed and arrested for a tantrum. That's a little overboard. I think kids should be arrested if say a 9 year old shot his friend in the face with a gun or stabbed someone or something then yes, the kid should be arrested, but throwing tantrums is part of being a kid even if they are sometimes violent. Adults shold be able to handle that situation.
But back on subject, if a kid knowingly commits a crime that an adult would be charged with I think they should be arrested and then sent to juvenile or some other place where they can be punished for their crime up until age 16 when I think they are old enough to be sent to prison. I know not all people are raised the same way but you should know shooting or stabbing someone by age 9 or 10 is wrong.