This is actually an Anglo-American gotcha, because it required bureaucracies in both countries to do it. This came to mind when reading a friend's account of bureaucratic woes involving her lost ATM card.
When attempting to purchase a visitor's Oyster card online - that's the electronic ticket card for London transport - I repeatedly got an error message when making the actual purchase. The message read as if the problem was with their system crashing, which is why I kept re-trying it, but eventually I followed a link to a phone number, which when I called it told me they were somebody else, not responsible for Oyster cards; but they gave me another phone number. After much expensive transAtlantic talk, they suggested I check with my bank.
I didn't see how that would help, but sure enough, it did. My card issuer had flagged that a purchase was being made in another country and blocked my card for suspicious usage. I said, "Oh" (this had happened once before with genuine fraud, and they'd reissued my card, which was a bear to deal with, since this was the card I had all my automatic payments on), "were you planning on calling me to let me know this?" Apparently the answer was, "Eventually."
It emerged - and I checked with my other card issuers and my ATM-card bank about this too, and they said the same thing - that nowadays they may block as suspicious any transactions out of country or even out of town (though they couldn't tell me how far out of town you have to go before this kicks in) unless the cardholder has previously informed them of travel plans. This puzzled me - I use my cards across the country all the time, and went to Canada four months ago with no problem - but I filed my plans with all of them. Dates; and country: UK only.
But that didn't save me, and this is the gotcha I came to tell you about. One of the things I did was drive the Dartford Crossing. This is the tunnel under the Thames at the eastern end of the M25 beltway around London. I didn't really have to take it: I was coming back to my hotel near Heathrow from Orpington, which is almost halfway around the belt, and decided to take the slightly longer route so that I could say I'd driven the entire M25.
The Dartford Crossing charges a toll, but it's electronic and with cameras, and the signs were clear: if you don't have an account, go online within 2 days, enter your license plate, and pay by credit card. So I did that, and it was declined. This time, unlike with the Oyster card, the error message was clear that it was my credit card that was the problem. Puzzled, I used another card, and it worked.
Next time I talked with B. on the phone, she told me that the first credit card's fraud department had called. Again. It turns out - get this - that though the Dartford Crossing is in England, the company that charges your credit card for the toll is in Ireland. And I hadn't filed a travel plan for Ireland. So they blocked it. My other credit card was less punctilious, it seems.
So does this mean that every time I buy books online from overseas, from now on, I'll either have to alert the credit card issuer first, or else use the other card? Apparently. In the past I've used only the first card for all online purchases, for security reasons, but until the Oyster card it was never a problem.
At least I got used to using the Oyster card and figured out how such cards work. There's a similar card for Bay Area transit, but I've never gotten one because I don't ride public transit here very often - about once a month on average, I'd guess - and because the instructions for using the cards sounded fearsomely complex. But now I feel slightly tutored. However, I read that, by the time I return to the UK, the Oyster card may have disappeared and been replaced by something even more bizarre and inexplicable.