Well duh. They have to comply with anti-money laundering regulation.
And yes, if you bought burgers and fries in the US you actually did pass KYC/AML laws, you are just completely unaware of it. The KYC (know your customer) laws applied when you created your financial account, your bank is obligated to check your identity before creating an account, and the AML laws are about monitoring financial transactions for something fishy.
Here in the US, you need a paper trail for deposits greater than $10k, and banks are on the lookout for “structured” deposits that side step this requirement. So buying a burger occasionally is fine, but if you started buying $15k worth of burgers a month, you’ll start tripping financial systems wondering if you’re doing something illegal.
As a practical matter, this is one reason why people joke about cash only businesses being a front. A cash only laundromat or restaurant is a fantastic way to clean dirty money for use in the us market.
Most likely a $10K deposit will be reported to the tax department by my bank. If they find that suspicious income they can then notify law enforcement or commence an audit. But otherwise it's no one's business how many burgers I buy.