The fact that the US has not upgraded is not an existence proof, it's simply one piece of supporting evidence. There are other possible reasons why the upgrade

The fact that the US has not upgraded is not an existence proof, it's simply one piece of supporting evidence. There are other possible reasons why the upgrade hasn't happened even if it makes overall economic sense - perhaps the cost of fraud and the cost of upgrades aren't borne by the same actors; perhaps there's some kind of game theoretic problem like a first mover disadvantage; perhaps the actors aren't acting entirely rationally. It seems like the upgrade of terminal equipment could be done quite cheaply if it was done as part of the regular cycle of equipment refresh, for example.