What do you think?
What would you have done?
Probably nothing would have happened had you told someone. There's really nothing that can be done. At one store I know of, employees can only "pursue" at a walk to the threshold of the door, although they'll often stand there and wait to take down a license plate. The objective is to de-escalate a situation and not provoke, as there are other customers and staff to think about. What little information is collected will be turned over to loss prevention, and this supports the company's shrinkage reports when they file their taxes--or can be provided to the police if the dollar value or harm justifies involving them.
A lot of it depends on what's stolen. My husband's store--who at the time was a retail manager--was robbed several times, including once to the tune of over $100,000 in less than 7 seconds. (His type of store was frequently scoped out by a more professional grade of thief.)
It might have been helpful to find the store manager and quietly report what you saw. The man is probably in there frequently and management is probably already aware of what he takes. I wouldn't think of it so much as snitching but a report made out of courteous concern. Some state laws allow for (what seems to me to be) a significant dollar amount on shrinkage, which probably allows companies to weather petty theft a bit better when they report their earnings to the IRS. The ability to write-off shrinkage helps in the long run and addresses how to handle the victimized entity, but no, it does not at all justify the man's actions. Rather, the manager can then go review the tapes and alert staff to keep an eye on the thief, and if his actions are deemed habitual or harmful enough, to have security escort him from the premises in the future.
If it were me, I probably would have leaned forward and quietly asked the cashier, "did he also give you those chocolate bars under his coat to ring up ?" But that's just because I often speak first without considering tact or some of the many variables that management has to contend with when considering whether or not to confront theft. Which may not be all that bad a thing. Had you done so, there is some possibility they would have wanted a statement from you--or maybe not. The marvelous thing about technology today is that it's all on video. But notifying management would have allowed their loss prevention team to secure the time marker and recording of the theft, so that it could be logged--if that is what their practice is, at least.
You know, I really didn't think I had anything to say about the matter & that this would be short. There goes short!