Founders can hold non-voting preferred stock and they can charge new workers membership fees. Rewards don’t have to be split evenly between people. The workers can jointly decide on an unequal distribution. The difference being the democracy rather than an alien legal party (the employer) unilaterally deciding.

Taking the risk refers to appropriating the negative fruits of labor. The idea that the employer is entitled to the fruits of labor because they took the risk is tautological