All three statements deal with the pragmatic aspect of public or business administration. Instead of discussing why someone should or should not do something, the signs--which are supposedly based on what works best for the businesses with which they are associated--give directives and expect adherence. They are similar to John Dewey's view of pragmatism.
The first statement is pragmatic because business owners and public administrators know that scare tactics often work, and most people would be frightened by the threat of having their vehicles towed. The sign does not offer exceptions (such as certain hours, etc.), and it does not try to discuss the morality of parking in a no-parking zone; it simply states the practical consequence of disregarding it.
The second statement is also pragmatic but does not solely rely on scare tactics. It offers customers a choice: Wear shoes and shirts and be served at the Bevo Shop; or go some place else sans shoes or shirts. It does not invite discussion and does not even cause one to ponder the moral implications (if any could be made!) of walking around without shoes or a shirt. Most likely, the sign is posted to not only ensure a modest atmosphere at the Bevo Shop but also for health purposes--certainly a practical matter.
The last statement is purely pragmatic. Most people like the business owners who posted this sign have dealt with too many bad checks, and to solve their problem practically, they completely eliminate the possibility of encountering anymore bad checks. The "no exceptions" tells the customer that there is no use in arguing or presenting an excuse.
All three statements address "problems" that numerous public officials or business owners have encountered and are most likely based on what has worked best in the past to curtail those problems--that is the essence of pragmatism.