The challenge for me with this sort of thing is that there is no formal definition of the terms. It seems set up to recruit people who may think they are cofou

The challenge for me with this sort of thing is that there is no formal definition of the terms. It seems set up to recruit people who may think they are cofounders, to work for free. But is there a written agreement about what exactly they own? If you are just getting volunteers they may not be the best fit, but still better than trying to do everything on your own. In which case, what do you do, just kick them to the curb if you start making money or get investment? That would be entirely unethical if you had led them to believe that they were cofounders.