They aren’t! However some of these premium retailers do have their designer make some or use fan art. Take the on masterpiece collection of dusk till dawn. The 2 full slips used aren’t poster art. Their designers have used images and made a design around it. FAC used @Noodles design for wolf of Wall Street. The homecoming wwa and new far from home wwa illustrated steels are from artists.
Manta realeased the WEA this year meaning they can use that art. But looking at kingsman, the way around to use that same art seems to be with a different finish. Hence why some are saying they wouldn’t be surprised if this is flat and matte like the kingsman rip.
In this situation it’s nothing to do with who’s designing what. It’s the wea principle that the art shouldn’t be used for possibly a certain amount of time. Considering manta released deadpool 2 this year with this art, it’s seems a bit soon. However I think the finish will be much worse
Which will make me and hopefully others who paid a lot more toward manta versions much happier (like it did with me for kingsman)