It’s funny you say that, because this scenario was how I explained it back in the day…
Imagine the US comes out with a shiny new quarter, it’s super cool, but won’t fit in any existing coin slot.
Upgrading one machine isn’t too bad if you know what you’re doing, but then doing every machine on a block, or a street, or a city, or a state? Suddenly way more complicated.
Oh, and they ALL have to be done by a specific date.