Do you have a citation for this? Tokyo has a high minimum wage (and low enough unemployment that most employers have to pay more than minimum wage), but I've yet to see an automated kiosk here.

Though in support of your point, when I went to Korea last year there was a large number of automated kiosks, and I know the minimum wage there is fairly high as well. So, Japan's lack of those kiosks may have to do with a preference towards cash/human interaction in the culture.