A number of years back, I wrote a small utility app for typing Hanyu Pinyin with tone marks (https://www.pinyinput.net) that I made available for free, with a 'Donate' button and exhortations that people could donate if they found it useful.
Despite 10s of thousands of downloads over a period of about 5-6 years, I could count on two hands the number of donations I got.
Then I changed it to pay what you want (including $0) with a default price of $5. And you click a purchase button rather than a download button.
Plenty of people still download it for free, but now it also gets a payment every day or so - sometimes $1, sometimes $5, sometimes more, but it's a consistent trickle.
I don't have much money to donate but I've seen some very compelling donation requests which wanted me to really start donating.
Patreon has also sounded very compelling to me.
Are those number not enough to start charging for more than #k requests? Even a few bucks a year to use the service would be better than nothing.
I think people just think other people will donate so don't really matter. I think that too for other projects, so it makes sense.
I nuked the spammers and shut down new subscriptions.