most of the self checkouts i have used in the past 5 years or so have not even included the "scale" as part of the process. i do remember maybe once or twice that being an issue but it almost never happens any more. 10 years ago they were all "scale stupid" but it seems like that died off at least here in the eastern US
the first time someone not expecting this surge pricing finds out they have to pay more because it's lunch time, they will not be coming back to wendys ever again