Ahhh, government software. The change would be in the numbers displayed... Seems pretty straightforward given how often they raise fares.

Well to change the fares they just change the amount deducted from the card. For this change they'd have to make a change that only applies to some of the machines. In a reasonable architecture that's a few lines in a config file plus some way of managing which machines get that file (possibly cumbersome if they didn't plan for this).

You're making a lot of assumptions.

Any comments on how easy or hard the change would be are.

Remember it is just a price change on the page. The machines are already online and they change prices with every fare change. I bet they can do it.