This is just my experience but in the situations where there is a price discrepancy it has on average taken less time for a correction at the self-checkout than it has at the regular check out. The only time I think I've had a very easy time in the regular checkout vs self-check out was at Target when I could pop up what was shown on the app and get a price match for it (on items that qualify for it). What I do think is more possible to happen at self-check out is the awareness of such a price discrepancy. With your attention on scanning the items yourself you may not pay as close attention to the price whereas when the cashier is scanning an item for you and bagging it your attention can often be singularly on what the item rang up as.
In the post you quoted the person said they had to go to a different place to get a correction, this means their self-check out area isn't staffed with employees who can handle it right there (which is not the case in any place I've presently been to). It's the case at the places I've been to if I'm at the regular checkout and miss a price discrepancy I have to go to the customer service desk (where it sounds like the PP has to go). I do think some stores make the process easier and some harder. I remember for a while there were some
Walmart locations near me where the cashier would have to physically walk back to the aisle to physically see the pricing issue, that was at the regular checkout and took way too much time, whereas the self-checkout employees would adjust on the spot.