One of my retail stories is that I worked as a cashier once with a similar situation; major difference was that instead of a pregnant lady and her Armed Forces hubby eating a wrapped sandwich it was a fat lady and her equally fat son each eating a donut. At the time we had an employee who was training for law enforcement, so he would "practice" in the store doing loss prevention. The day in reference, he sees they're in my checkout lane so notified the manager in person (intercom would give away his actual status as an employee), manager intercoms me, says "don't say anything but let me know if they pay for two donuts or not" and when they didn't, I intercom him saying so and they nab them right at the door. I don't know for certain what happened, but I know no police were called, no one was arrested, anything like that.
As for the general policy, while it may well be allowed to do so, it's probably not the smartest thing to consume something without having paid first; I know I was quite annoyed by having to contend with these half-opened items (barcodes being folded over themselves or whatever else, making them much harder to scan than had you exercised enough restraint to withhold your primal instinct to devour said items until AFTER you paid for them)...
As for the general policy, while it may well be allowed to do so, it's probably not the smartest thing to consume something without having paid first; I know I was quite annoyed by having to contend with these half-opened items (barcodes being folded over themselves or whatever else, making them much harder to scan than had you exercised enough restraint to withhold your primal instinct to devour said items until AFTER you paid for them)...