Just so you know, the Matt3o key caps are not SA. They are a unique profile he developed himself called mt3. Additionally, the shining you mentioned isn’t because of a difference in quality so much as a difference in plastic type. These SA key caps are double shot, a very premium and long lasting way of creating the lettering that works by using different injections of plastic for the letter and the rest of the keycap. This is necessary for key caps with a lighter color letter than background, as you can’t dye something with a lighter color. However, using this method necessitates the use of ABS plastic, instead of the more durable PBT plastic on the Matt3o keycaps.
Because of of the thickness and tooling costs, this SA set actually costs more to make despite the cheaper plastic, and many people put up with the shining for its benefits. Rest assured though that it’s literally impossible for the lettering itself to wear through as happens on cheap $10 keysets, and if it really bothers you that much I’ve heard that some people have taken to sandblasting their keycaps to remove shine.