They use sprout inhibitors on large scale potato growing, which are effective in my area (we can keep most potatoes for over a month before there are any sprouts). If you tend to buy from farmers markets, there is a greater chance of them not using inhibitors.

Depending on where you live, they can be in transit for a long period, or you may be in an area that has natural pressures for sprouting.

Short note on sprout inhibitors: https://www2.gnb.ca/content/gnb/en/departments/10/agricultur....