In our experience, people in Mexico don’t stock up on items like they do in the US. There are several reasons for this. First the refrigerators are much smaller than they are in the US. Second their approach to money is usually to buy just what is needed for the moment. Third, there are small corner shops making it easy to run across the street to buy something you need. Fourth, there isn’t always an advantage to buying in bulk–1/2 gallons of milk is exactly half the cost of a full gallon.
The place where buying on demand is most noticeable is when you look at how the locals approach phone and cable services. It seems like many of them pay for the service and use it until it gets shut off. Then they pay again and are good to go for another month.
That wouldn’t work in the US because of the additional fees of getting service re-instated, but at least in Durango it seems to be very common.
I suppose the low cost of labor helps feed this. Also if everyone does it, it would be difficult for the phone company and cable company to start permanently blocking customers who don’t pay on time without losing a lot of their business. Another thing to consider is the poor mail service. You often won’t get a bill in the mail, so turning off service is the companies way of letting you know it is time to pay.