I think people are far more invested in trying to find some conspiracy instead of accepting that mistakes happen, be it in code, pricing, whatever.
The closest thing to a fix is ensuring your local consumer laws say the sticker price prevails and call it out to a supervisor if you find an issue.
I don’t get the weirdness of the spike of self-checkout hate lately. There’s a lot of “I deserve to have a human scan items” takes that are bafflingly stupid.