Although they will return the funds if you file a claim, I wonder if they pay interest owed since the funds were seized.
One would think they could target those fees instead. There's little doubt this is also about the government collecting interest on the funds, and keeping those that are never claimed.
That's funny because we do the exact same thing in the States, it's called escheatment, and it happens on any account that has lain dormant for a period of time. I also think it's up to the bank to define "dormancy" in terms of account status - it usually means 2-3 years of not logging in/not contacting your bank/no transactions on your account. The timeframe after the account goes dormant and before it is escheated, plus the guidelines the banks have to follow for the escheatment process, those are going to be your state-regulated laws and regulations.
As far as I am aware it seems to be a process more of state enrichment (potentially) than "saving your cash from bank fees" as it is a process that has been in place for a very long time. Also, at least in the U.S., no, you will not get paid interest on escheated funds. (So if you want to put money in a hole and forget about it, put it in long-term CDs with automatic rollovers - those rollovers should count as activity and prevent escheatment/dormancy. In addition you're likely to get a high interest rate.)