If you wish to believe that the case depicted in Neighbours is exclusively a fictional case, then you can do that. There are surely exceptions, and setting a line is probably not the best option. I know of 20 year olds who are less capable of making decisions than 14 year olds.
However, I will not let it rest on my conscience that I could possibly be denying the rights of a couple, when I should have no hand in it.
Also, just because you regret previous choices, it doesn't mean you weren't aware of the choices. It is your personal experimentation with your choices that improve your ability to value and judge choices in the future. You would not have learnt to regret such choices had you not been given the opportunity to do it. I never said that both adults and the youth somehow have the ability to always pick the best choice, I just said that they should be able to make choices, and be responsible for them.
I believe that we do make better choices as we grow older, I did not deny that, but it is experience that improves how I make my choices. Experience comes with the act of exercising my rights. If I am unemployed, how am I able to gain work experience?