Well, ok, not a thief as such, but they'll still happily take your money without asking!
When we came over here we opened up bank accounts for our two kids, putting money in that they had saved up from England. They had about $1000 in there each. After a few years we realised that the amount of interest they were getting paid was truly pathetic (0.01% I seem to recall) so I had a chat with the bank who moved all but about $1 into a new type of savings account for them, with higher rates. The original accounts needed to stay open as you couldn't have a savings account without one of those sorts too.
OK, so daughter has now grown up, done a bit of paid work, taken control of her own account, and uses it to pay into and out of. Son however hasn't started any paid work yet, and any money he gets for birthdays/christmas/chores etc gets spent pretty quickly, so never sees the inside of a bank.
Yesterday he gets two letters from the CBA saying as his accounts have not been used actively for the last three years, all his money has been transferred to the federal government. Now I know (now!) that this is the law these days, and it's all automatic, but you'd have thought it was common courtesy to let us know before they did this, not afterwards. Especially as my name is on the accounts as well, and I have several other accounts with the same bank, same branch, same surname, so all it would take would be a simple bit of human intervention to look up my telephone contact details and send me a quick warning text message, surely! Funnily enough, they transferred the money and closed his accounts just a few days before his 16th birthday, almost like they hoped we/he wouldn't notice!!
So now we've had to fill out countless forms to reclaim his money, then more forms to open a new account for him (hey, guess what - 0.01% interest again) so that the funds have somewhere to go when they come back (as otherwise it would be sent as cheques which the bank would charge $5/cheque to pay in - even the one that will only be for about $1.50 face value), and then start all over again with finding a savings account that will pay a bit of interest, and then more forms to open that.
Moral of this long story - if you have an account with money in it earning interest, don't assume that money is still there! It could be part of the fundsbeing used to soundproof a greek church with $5mio worth of egg boxes...
Arrrggghhhhhhhhh............ I HATE BANKS!!