If they were searching for gift cards why would they care what else you had(that obviously was not stolen from the employer)?
Personally, I kind of doubt that wallets are routinely checked at the stadium. It takes more than a passing mention on a tech website to convince me.
Even if they aren’t activated, if they have a high value mark on them they can be sold “at a discount” to people who don’t know they aren’t activated and who will have no recourse when they find out.
Meet me at Kennywood; I’ll bring the plastic can of snuff. You can doubt all you wish but I’ll put cash on it. After you pay up I’ll get my one buddy to show you a collection of the things they have caught; you would probably be surprised.
I won’t name the company because this isn’t really a positive comment but think a major internet shopping source named after a South American river and region that is well known for being TOTALLY NUCKING FUTS when it comes to security. As I understand the logic, the thought was that I could use the membership cards as cover to sneak out some gift cards or things like that. Get people used to seeing the size/girth and then use that space to take whatever valuable would fill that space. And the security manager just couldn’t wrap his head around why someone would carry all their membership cards at once. Many carry rebates and discounts, some are for access to club buildings and grounds, and I find it easier to keep them all on me rather than think ahead “Which ones may I need/benefit from today?”
Any other misconceptions I can cure you of while I’m at it? 
Yep. I refuse to visit Kennywood again exactly because of the absurd levels of security. It is an amusement park, not a nuclear installation.
But after being there for the opening day “riot” and one of the other incidents this season I’m not as sure its overkill as I once was. Although as unsecured as the perimeter is I’m not sure there isn’t going to be something really bad there some day. They aren’t alone though; Six Flags Jersey is pretty tight-assed about it all at the front gates as well - among others. It’s gotten to the point I just usually pile everything in my hat and let them do their “stick thing” with it where-ever I see those full walk-through set-ups.
One guy tried to sneak a bomb onto a plane in his shoes and we all still have to take our shoes off, ten years later.