not possible to place a Shreiker that is man maded summon a warden in survival some one might have made some super elaborate contraption of redstone and stuff to make a shrieker get tricked into thinking it is real but to my knowledge its not possible in survival
I'm not sure if your referring to 1.21 or why do you have to do it with command. If your reffering to 1.21 they re did the command argument structure so this probably won't work anymore. If your talking about why it wont work without the command in 1.20 thats because they dont want people in survival to be able to spawn wardens wherever they want.