It may be because the very tight housing of betta fish is already so normalized that these conditions are not shocking to people, or PeTA has just burned too many bridges to be taken seriously, or fish don't evoke the same emotional responses as furry mammals.
Regardless of how you feel about PeTA, their basic message that these fish like a bit of room to move, and can be housed socially with suitable fish, is one that should be more widely appreciated.
