Disclaimer My informed opinion is not that informed. It falls within a little knowledge can be a dangerous thing😁
IMO Its possible in that case that the party had a number of cash lodgements that the banks automated system did not like. Once flaged the bank had to go through their internal process. The law/process specifically excludes the bank from asking the account holder to justify the transaction(s).
Generally its a problem of mission creep and cost.
Anti-money laundering covers any money generated from or for criminal activity. Eg. Not paying tax is illegal ⤵️
www.gov.uk/government/publications/publishing-details-of-deliberate-tax-defaulters-pddd/current-list-of-deliberate-tax-defaulters
So by default the banks should be taking the tax defaulters list and closing down bank accounts associated with these people. The bank should also be looking at the accounts the money came from. Was the originator aware of the tax default? If so that's the first part of the tax evasion.
Then the outflows need to be examined. Did the recipient know that some of the money paid to them was stolen from the public purse?
If so thats assisting in money laundering.
The bank will risk assess the cost of getting it wrong and the cost of doing it right eg compair the fees earned off the a multi-million client account against a working class account.
When is it not economically viable to do indepth research; by a highly paid professional/manager level employee; with the risk of still getting it wrong? But once flaged the bank has an obligation to hold on to the money in the account and investigate. Sometimes it could also be that the Bank make a report to HMRC or police and then have to wait for that independant investigation to reach a conclusion.
For low value accounts its going to be cheaper to reject the account holder on social assessment as well as a financial assessment.
In Canada the demand was that the donors to the political dissidents be tracked via their financial data. A single transaction traced back to source, from that data the government should be allowed to freeze money in the account (no food, light, heat, shelter) and go after motor vehicle insurance (independent travel) etc. The public did not really blink and think if you want to do that to them you will want to do that to me too if we don't agree.
The link from donation to the motor insurance is 1 database query.
The computer system's ability to analyse data will also link family, friends and associate's data together. We alread see this if you live at an address linked to fraud etc. Insurance products will cost more if you live with someone with a criminal record.
If the bank (senior ee's, rich, insulated from poverty) have the data capability to eliminate risk by adding in a social credit element why would they not do this?
The bank has a social profile of what customers it has and a strategy of the ones it wants. Apparently part of the strategy is now to tell customers to fuck off.🤷🏼♀️