When leap seconds are added, this would require manual changes which I'm sure cost lots of money to change, test, verify, etc. Kind of like a mini Y2K, where they spent lots of money merely to make sure that things didn't change.
Who would care if they didn't add the seconds? Just ignore it.
Many GPS receivers have a "1pps" (one pulse per second) output line that gives a one second tick that's nanosecond accurate. This is what's used to syncronize stuff.
Bank transactions are apparently pre-scheduled to occur at time such and such, so as to match another corresponding transactions going in opposite directions.
The GPS UTC conversion value downlinked to receivers is the *current* GPS to UTC difference in seconds. When that's changed, the change does not happen instantly. So at a minimum, when the leap second is added, all bank transactions would have to be halted to wait until the new GPS to UTC difference to be recieved by everyone.
Since leap seconds are added at random times (because there are all kinds of irregularities in earths rotation), time changes are a manual process where systems people would have to shut things down, then bring them back up after the time was changed.
It wouldn't surprise me that the whole thing would cost tens of millions to do, worldwide.
Sorry Willie, but it's silly to spend that kind of money just to make you feel good about the time.
They probably don't convert to UTC for the transactions themselves -- why step out of your internal time source? They very may well convert to UTC for output purposes, however, and that's a far easier thing to handle.