no way will they go back to coin-operated. That would mean they have to pay employees to walk up and down to collect coins.
The other problem, in the US at least, is that cash is very low value (inflation), and dollar coins never caught on. I'm not trying to carry around $6 in quarters to park for 2 hours. And that's a pretty inexpensive parking spot.
And maintain them, which I suspect costs even more. Parking meters do fiddly work, out in all weather, where people hate them and do all kinds of vandalism.
It doesn't surprise me that they want to make hardware maintenance your problem.
And worst of all, the momey you pay isn't tied to your license plate. If you overpay, someone else can park for free!!