pngcrush is fairly old. And terribly unoptimized. If you want a command line solution, I recommend optipng (which does what pngcrush does, but better), and sending the result through advdef, which improves the compression even further.

...but really. ImageOptim is super awesome and zero-effort.

Super awesome yes, zero-effort no—just try to make it into part of an CI/CD asset build pipeline ;)

But really, why isn't ImageOptim itself available in command-line form?

IIRC, ImageOptim is a front end for a bunch of CLI image compression tools. So, in theory, you could roll your own for a CI system if you figured out all the arguments that ImageOptim was passing to those tools.

This looks promising:

> Automates ImageOptim, ImageAlpha, and JPEGmini for Mac to make batch optimisation of images part of your automated build process.

https://jamiemason.github.io/ImageOptim-CLI/

> automated build process

> Mac

Why would anyone run a CI server on a Mac?

Perhaps it's just their preferred platform. If it weren't for the expense I'd probably prefer it over Windows at least. At any rate, the readme does link to this article[1] if macOS isn't your thang.

[1] https://addyosmani.com/blog/image-optimization-tools/

You need to if your product is a macOS or iOS/watchOS/tvOS app.