Interesting thought, but I’m not sure it’s workable.

For one thing, it’s unlikely Medium is spending $4 out of each $5 (80%) on author payments. With no advertising, membership fees are presumably 100% of their operating income. That has to cover all (or nearly all) expenses, of which author payments are just one component, with some profit left over. At a rough guess, author payments are likely 40% of income at most ($2 of each $5), and maybe as little as 20% ($1 of each $5). If the CFO is watching, feel free to correct me on this. ;-)

I’m not sure it would be a feel-good proposition for readers to have to decide how many pennies to give to each of the authors they’ve read that month. If it was put in percentages rather than actual cents, that might feel better. But how many readers would complain about needing to take the time to divide up their payments each month? How many would forget or simply refuse to do it? And what would the default division look like if a reader fails to do it? It’s probably simpler all around to automate the payments, even though there is no perfect system for doing so.