I could never figure out why many (maybe most) G-Shock watches do not have the text "G-Shock" anywhere on the case back or on the display. It exists only on the resin bezel on most.
The only one I have that has G-Shock on the actual display is my MRG-200T.
I also have a GW-M5600 that has a large G on the case back followed by a Shock Resistant crest but not the actual word G-Shock.
Casio however, always appears on the case back and display in my experience.
Also it seems strange that Casio still appears so prominently since the brand G-Shock is so distinct from the Casio brand. It is a bit like Bentley's and Bugatti's having a VW Audi Group badge that is more prominent than Bentley or Bugatti on their cars. To me the Casio brand badges somewhat devalue the G-Shock product.