I suppose it has to be frustrating to know your 16 year old child is stealing from you. Or is it more frustrating to know that your child is taking drugs. From your post, it seems that you're more concerned about money. Please don't think I'm judging you, I am not in that situation so I wouldn't know.
To wonder what it is that has made him even choose to take the drugs in the first place, i mean what must be going on in his head! What are his troubles?
And when the police were there, why did they not offer any options to get him help. I would have asked at least while they were there-you do pay taxes. I would have been insulted if they told me what they told you.
What I can't figure out, as a parent myself, is your statements about your child being put on probation and you having to pay the fees and finally, "I just hope it isn't wasted".
Is that a thoughtful way of saying that he is going to fail-you know relapse? Some drug users do relapse several times before succeeding. Some of our failures end up being our successes.
Anyway, like I said, I'm not in your shoes, so I really don't know what your thinking. I do wish your family success especially your 16 year old child.