Seems like focus is on a scaled Worker Cooperative. Might be helpful to specify this so that readers know the emphasis and scope. For instance a platform cooperative could take many forms, worker, freelancer, consumer, producer or a multi-stakholder mix. The question to whom should be members comes down to if they are a real "stakeholder" in the organization or if they contribute long term value to the platform. Also if both they and the enterprise would benefit by their participation as cooperative owners.

Best way to accomplish this to make sure cooperative goals are still inline with interests of the individual members, even if there are different classes that have different interests. Like a dairy cooperative is aligned with the independent dairy farmers goal to sell more milk and have a higher net profit, while still maintaining their community goals.

Even if the day to day transactions of the platform function as p2p because cooperatives are legal entities with clearly laid out governance (bylaws, membership agreements, a board of directors and some kind of management team) there is a way to enforce standards. There is also the option the utilize volunteer committees to address standards and practices.

Also about shared legal ownership. In the early stages probably more of a concern as members would have higher levels influence and company culture and processes aren't set. At scale though barriers to entry could be quite low, consider a Cooperative like REI has a very low barrier ($29 and signing a form.)

The surplus left over (after all business expenses, reserve allocation, etc) is net. What is allocated to the member based on their percentage of "patronage" is their patronage dividend. Much of this is about the tax status of cooperative so not sure how that equates across borders. More on the actual tax related definitions of how patronage dividends work can be found here. http://www.dmlp.org/legal-guide/taxation-cooperatives-and-patronage-dividends

Paying into the patronage fund? Is this in reference to capital contribution required by a member? If it's equal for all member in a certain class then if its not paid would be more of a violation of the member agreement and it's assumed there would be procedures to rectify the situation in the agreement.

By tracking contributions as the patronage this is not longer an issue. Patronage is usually reset each year but could have other ways accruing. Like a consumer cooperative if a member doesn't contribute anything in a fiscal year they wouldn't be eligible for patronage dividends.

Patronage really is the contributions or the "business" that a member does with the cooperative. In a producer cooperative that is usually supplying raw materials (milk, grain, etc) to the cooperative. In a straight consumer cooperative that is usually purchasing but it could also include promoting or volunteering. In the end the patronage has to be able to be measured in some kind of quantifiable unit (time, dollars, tasks completed, etc). This way measuring a members patronage is a percentage of the overall member contributions.

Freelancers have the most clear identifiable need for Platform Cooperatives as the cooperative was first envisioned to solve a market problem faced by independent (consumers and producers). In an age when more and more workers are freelancers the need has risen in proportion to the rise of large extractive platforms that connect freelancers to their audience.

Not necessarily. It needs to be owned by the primarily stakeholders it serves. For instance an AirBnb type platform coop might be owned by the home owners (producers) and by the renters (consumers) but not by the workers that administer the platform. Why? Because they are the primary stakeholders that provide the value to the platform and whom rely on the platform to do business. Also in some ways the workers are already protected (by labor laws) and the fact that they are compensated up front for their contributions.