We have these things by us called grocery stores.
OOT grocery stores run out of CY (aka super kosher) milk. Often its only delivered once or twice per week and sometimes not even..
Growing up in DAL 30 years ago, CY wasn't available. I believe we got it a couple of times per year from Chicago. After that in in STL 25 years ago, we got it once a month delivered to someones house.