[jakub_g]

Note that it's not only Apple who's been slow to adopt WebP. Mozilla was pretty skeptical for many years and only implemented this ~a year ago (instead they did a lot of improvements to JPEG encoders in the meantime).

At this point I'd be more interesting in Safari supporting AVIF, though for compat reasons WebP would be nice to have as well.

I'm not defending Apple, but I think the issue is that if Apple implements a new file format, it has to work reliably across whole Apple ecosystem (OS, image editing programs), not only in the browser. This is probably a huge undertaking. You don't want to download a picture and then your image viewer not being able to open it.