MONEY ****** FROM WALLET LEFT IN CAR

My sister-in-law hired a vehicle from Avis from Monday 5 October to Wednesday 7 October while on holiday in Cape Town from Johannesburg. My son accidentally left his wallet in the vehicle when it was returned on Wednesday. He only realised that his wallet was missing on Friday. I immediately phone Avis and spoke to Clayton, who was very helpful and efficient, he then confirmed that the wallet was there. I told him that we would come and collect it on Saturday. My husband collected it on Saturday in a sealed envelope and when he got home I opened the envelope only to find that there was not a cent left in the wallet, it was cleared out! There had been about R130 in the wallet, I know this is not much, but to a 13 year old it is alot, and anyway, it is the principle behind it. Who gives them the right to remove the cash? So, whoever finds the wallet clears it out and then hands it in to lost property? The sad part is that this seems to be the norm these days, I sort of expected the wallet to be empty, but is this how it should be? An incident like this does not give a young guy, like my son, much faith in his fellow citizens, now does it?