For instance, a developer could quote Price X to non-technical co-founders to develop a simple, proof-of-concept MVP with an agreement to would receive Equity Y upon completion if the developer either (1) stays on for Period P or (2) helps the founders successfully land a more suitable, long-term developer to take over the project. The parties could even agree that Equity Y would be larger (e.g. 2Y) if the developer stays on.
Benefits to the non-technical co-founders would be (a) a proof-of-concept (or failure), (b) alignment of incentives with a developer to try hard, and (c) access to an insider to help find a permanent developer upon completion of the MVP if the MVP developer wants to exit (e.g. for a better opportunity).
The benefit to the developer would be (i) guaranteed fees, (ii) potential for equity (even if he exists) and (iii) flexibility.
More, a subsequent developer would have the chance to deal with someone who speaks his own language in the negotiation with the non-technical cofounders, and could avoid and annoying and/or exhausting translation of technical details.
An obvious objection may just be that non-technical co-founders never have money to pay for an MVP. I am far from an expert, but I would think that some do.