You just linked something that doesn't have anything to do with what I just said.
If you are 18 and under 21 you can be prosecuted either as an adult or a young adult. Being prosecuted as an adult means you can be charged with what you did as an adult. If you are prosecuted as a young adult most of your charges are dropped and accommodated to give you a chance of not repeating the same offense again.
If a 18 year old gets caught while committing a burglary he's going to get fined and prosecuted as a young adult, he'll have to talk to social services every once in a while and that's it.
Now, if the same 18 year old committed a serious crime he will be prosecuted as an adult.
I never said you can't be prosecuted, just that you are prosecuted differently.