There are 100 people in a room. They have $10 each. The academic speaker will give them a talk but the venue wants $50 to cover its costs (and any profit/surplus). There are 40 such talks per year. There is final indefinitely large group of people (let us call them “the general public”) who might want to hear the talk but who can’t afford to pay anything.
Subscription logic: each person pays $0.50 and gets access to the talk. If a person does not pay, s/he/they may not hear the talk. This logic is implemented to introduce a classical economic sytem. With the funding available, each person can choose to attend this talk or another. However, each of the 40 talks is different and doesn’t cover the same material. The attendees do not really know whether a talk will be useful to them in advance. They can attend 50% of the talks. This model spreads costs but limits access; 50% of the talks could be attended by 100% of the attendees but nobody from the “general public” group gets to hear the talks. Further, it is unlikely that all 100 participants will attend the same 40 talks, so knowledge of the talks’ contents is diffuse. Some believe this is the best way of ensuring the venue is compensated and remains open for talks because it incentivizes people to pay. The speaker doesn’t necessarily get the largest possible audience from this model.
Article Processing Charge (APC) logic: the speaker will pay the venue’s cost of $50 and let anybody hear the talk for no charge. This makes sense to the academic as her only motivation is to be heard (she is one of the lucky ones who has an academic post). The problem is, she only has $10 herself. This model concentrates costs (sometimes impossibly so) but allows the theoretically widest access. In this particular case, though, an idealised logic led to no access since no single individual can afford the total cost. APCs have a problem of the current distribution of resources.
Consortial OA funding logic: 5 people attend each talk. They each spend their full allowance of $10 on that single talk. However, they let everybody else attend any talk for which they have paid, in expectation of reciprocity and for the public good. They record the talk and let others view this for no charge. This model spreads costs and allows broader access than the subscription model; 50% of the talks could be heard by not only 100% of the attendees but also by the group who can’t afford to pay. This is the logical choice for those present but some are worried that they may pay while others might not return the favour.
There are also arguments that the $50 venue fee is extortionate, since it appears that 35% of it ($17.50) is pure profit for the venue organisation, which is in fine financial health. Some point out that were this closer to 6% ($3.00) the organisation would still be fine and could pay all its staff but each talk would only cost around $35. At that rate, it would be possible to host approximately 29 of the planned talks and, with the distribution in the different models, allow other groups to have access.