It isn't just cash withdrawals or depsoits. I had huge problems buying a house because the cashier wanted me to produce an invoice for the deposit CHAPS transfer (we had done everything with the solicitor electronically, so I didn't have one, had to kick up a huge stink to get it to go through).
Another time I had them asking me what a large some of money I wanted to transfer from my savings account to my current account was for. I said "stuff", they said "it's a lot of money to spend on stuff" so I said "I'm rich" (not true).
I also had an odd discussion with fraud team once who I received a call from following suspiscious activity on my account. They wanted to know what I had withdrawn £500 for - I said it wasn't any of their business and they said "it's just a security question", so I asked how it could possibly be a security question when they couldn't have any idea what I was going to spend it on. It was quite odd.
It does make me irate. Mainly because the people asking these questions either don't seem to understand why they are asking them or they lie to me about why. I haven't had a cashier sayt o me, "I'm sorry fi it seems intrusive, we have legal obligations to try and get to know your financial business because of money laundering regulations" it's always "I'm only trying to help" or "it's for your security" niether of which make much sense to me for the questions they are asking.
I would also be less annoyed by it if they didn't seem to use every bit of information about me to try and make more money out of me regardless of whether or not they are actually helping me and often by misrepresenting. 30 years ago I liked my bank and would have turned to them for advice. Nowadays I assume they are a bunch of sharks with no interest at all in my financial wellbeing, only in how they can get the biggest percentage of my money, so I'm not inclined to think well of their attempts to interrogate me and I trust little fo what they say. This isn't down to money laundering regulations, it's down to the appalling practices of high street banks over the last two decades. So I don't think claims of "poor banks are only enforcing the law" carry much weight. They don't only enforce the law, they also abuse their position to my detriment. If they didn't do this so much they'd be able to enforce money laundering regulations without getting people's backs up so much.