I can't really fault UD for the lack of licensing for "Letterkenny". They likely could only use these photoshoot style pictures. No images from the actual show.
And yes, it's disappointing that Keeso and Trevor K Wilson didn't sign. But it's hard to get non athletes to sit down and sign a bunch of stickers.
Speaking as a non-sports collector, I was super happy to see these cards in the product. The fact that UD recognized this very niche Canadian comedy is awesome IMO.
