In this area, it's a matter of weather. We get to about 115F during the summer, down to as low as -40F in the winter, and very little weather in-between, so there must be doors to help regulate indoor temperature. The local Wal-Mart has to lock certain doors on windy days because otherwise people would have a wind tunnel, and we frequently get rain and hail. There was also a manhunt nearby last week for a triple homicide suspect, and all businesses and public buildings were locked down so that he would have nowhere to hide and would not have the opportunity to take hostages. Maybe that's one reason why it's a business requirement?
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