I dunno why... but i've fixed the pier and put the fishing bags in place.. and yet.. no fish have been caught to date.
I dunno why the players keep thinking that they should get the fish. You got the task to fix the pier and to place the traps (that you were given by the village). When you finished the task you got paid and the villagers (Alice) now start selling the fish. I think it's quite logical.
It's like if you ask to repair you car and pay for the repair only to get the message "Oh, I've fixed your car, now it's mine."