Color Catchers and Synthrapol are not intended to stop loose dyes, they merely keep what's already come loose and is floating in the water from settling on and 'recoloring' other fabrics. That they sometimes 'appear' to stop bleeding after multiple washes is only because the fabric had shed all of its loose dye anyway.
Retayne and its clones are the only products that actually set the dyes used in today's fabrics. Salt and vinegar worked many years ago on old dyes, but not on the newer ones used today. It's all based on the chemistry of the dyes.