Why? If every person participating is giving $10-$20 per month to tens or hundreds of projects and then once distributed, this equates to $x00 or $x000/project/month, why would the payment processors mind. Of course, it's all in theory.

they charge a minimum fee per transaction. from Accursed Farms' donation page (https://www.accursedfarms.com/donations/)

"Paypal keeps $0.30 + 2.9% of every donation, so please keep anything less than $0.32 as they have enough money already."

i think Cash App has the lowest fees i've seen at like $0.01 which would still be too much.

not saying it is impossible - but likely not viable directly with the current payment providers.