I remember quite some years ago. My bank had an option on the internet banking to say which country you were visiting to cut down the automated fraud systems. I visited Namibia, put all the details into the system. Went to an ATM once there and instantly declined.. 10 minutes later I get a call. The guy says "You should have told us you were going to Namibia", I said I did... "Oh, yeah... OK it's all good now".
Automated systems also are weird and unpredictable. Spend 10k on a car on the card for the first time ever? Sure we won't even manually approve it, just take the money. Spend £50 at a retailer you've used regularly for over a decade? Yeah, we're going to decline that. Yes, this really happened. I mean, I'm sure there was some really good logic going on there to do that. But, I can't fathom it.