I beg you, if you are a developer of an open source app or program - add screenshots of your app to the README file. When looking for the perfect app, I had to install dozens of them just to see what the user interface looked like and whether it suits me. This will allow users to decide if the app they choose will suit them… Please, don’t think about it, just do it…
I think that doesn’t work for most smaller projects. That’ll work for something like Firefox, but there’s little reason for random, unheard of tools to have an image on the web. Plus the naming of some projects is super generic, which can make it hard to find correct images.
Some software changes appearance often, too, and google is bad at knowing what up to date is. It can be really easy to find wildly out of date images as the top results.