Those U.S. finance jobs tend to be "domestic retail operations" like small-town bank tellers, whereas U.K. finance jobs concentrate more in international finance and investment banking.
So why are the U.S. jobs more at risk? They seem to think what the tellers do is simpler than the "international finance" people.
But simpler does not mean more automatable. In theory bank tellers across the U.S. could have been replaced long ago by the ATM - but as we all know ATMS are everywhere and that has not happened. What is left for tellers to do at this point is the one thing that is going to take longest to really automate - personal human to human services.
Sometimes a bank customer use has a question and an ATM cannot just answer that. In fact I just got a higher end credit card and one of the features it offers is that calling the 800 number immediately connects you to a human - no voice menu. Automation was supposed to be the end of that kind of thing but it just led to higher end jobs.
Meanwhile those fancy "international finance and investment banking" jobs sound like much more specialized jobs which means they are more open to automation, and probably doing a better job at it since there are no language barriers for computers (though system barriers may be similar, they only need to be overcome once rather than per employee).