The point is that saying "pull requests welcome" is still work for the maintainer, because now you have to have these discussions with potential contributors, sometimes explain them why you don't want to maintain the feature, or explain them why this PR is not the way you want...
So either way it's work, it's important to keep in mind before saying "just send a PR".
The problem is when people then open huge PRs and expect you to take time to review them, then eventually merge them.
Especially when it's something you don't want in your codebase because it introduce a big unnecessary "refactoring" or a feature that you don't want to have to maintain forever.
It's not a lusty image if nobody knows what the full picture looks like. Hence the reference to the Streisand effect.
What I'm not seeing in this thread is the reason why this picture is so over used.
One reason is that it's the perfect image to test graphics manipulation algorithms like compression for example. It has all the characteristics you want to check for: various textures, gradients, lightening... It's like the benchy (3d printing) of image compression.
The other reason is that once it established itself as the reference image, it was easier for researchers to compare algorithms and make sure the author doesn't cheat by cherry picking a picture where his algorithm is clearly better.
Researchers were used to see the common pitfalls of compressions algorithms on this image (the fur for example).
At least on my country contactless with a card only works up to a limit (€50). Beyond that amount you need to input your pin code.
With a phone, no pin code. With a smartwatch either, and that's my preferred way. No need to pull anything out of my pocket.