Conventional wisdom is that only a copyright holder of included GPL code could go after a publisher that breaches the GPL (by claiming copyright infringement). However, recently there's been a lawsuit brought on grounds of breach of contract, which allows any user to be the plantiff.

That case is set to go to trial next month, so I guess wait and see if SFC succeeds and then, if it does, you could sue those app makers yourself and cite SFC v. Vizio as precedent.