The donation banner on Wikipedia made me think of this story I read in a marketing book couple years ago:

A large national park (in Arizona or something) was having a littering problems. They decided to run a campaign to combat this. They put up signs in the park that read something like "X thousand people visit the park daily and litter Y tons of garbage. Please don't litter".

That did not help much. In fact, the book claimed that it made the problem worse compared to having no sign at all.

Then they changed the sign to simply read "Please don't litter". And that did help compared to no sign.

The reason the first sign doesn't work is because it normalizes the behavior that it's trying to discourage. As in "it's no big deal if I litter a little bit, sounds like everyone else does it too"

I wish I remembered which book this was. Maybe Made To Stick? This was couple years ago. I read half a dozen marketing books on top of each other so it could be any one of them.

The point it's making about marketing copy is that it's better to spell out the action or behavior you're trying to encourage. Not the one you're trying to prevent or discourage.

Coming back to the Wikipedia donation banner I saw yesterday, my hunch is that it doesn't convert well...I can imagine it rubs people the wrong way and even feels a bit manipulative by making use of guilt.

Instead of this (with all the negative copy highlighted)

Hi reader. This is the 4th time we've interrupted your reading recently, but 98% of our readers don't give; they keep reading. This Wednesday we ask you to protect Wikipedia's independence. All we ask is $2.75, or whatever you can afford, to secure our future. We ask you, humbly: Please don't scroll away. If you are one of our rare donors, we warmly thank you.

I wonder if something like this would be better

Dear reader, glad you're enjoying your 4th wikipedia rabbit hole today. Please take a minute to donate using one of the payment methods below. It'll only take a minute of your time. You can contribute as little as $3. It's a tremendous help and protects wikipedia's independence.
Thank you! We appreciate your thoughtfulness. Now on you go with your scrolling.