This isn't a credit card error. This would be like signing a contract with Sprint for 500 minutes a month for $20, getting charged the $20, and then being charged an extra per-minute fee that wasn't in the contract.
Kind of like when you get your latest Comcast bill, Sprint bill, natural gas bill and see that "effective $DATE we will be increasing our price by $X% due to $Y". Happens all the time unfortunately.
It doesn't happen like that though. Natural gas, sure. Power bill, definitely. I've never had natural gas or electric service where I entered a contract for a service at a fixed price. My cable and cell phone service are on a contract, they can't increase the cost during the contract period.
Maybe I misunderstood, but this doesn't sound like a credit card error. The charge was intentional. The stated error was failing to notify some people. The actual error was thinking that you can charge people's credit cards without their consent just because you gave them notice.
Instacart makes a mistake and writes an apology on its company blog. I wish I lived in a world where there were more Instacarts and less Sprints.
People are fallible. Companies are fallible. The real indication of character is what they do to fix things when they go wrong.