JPEG-XL is better for images, no doubt. However it lacks the political backing that AV1 and hence AVIF has. It’s sad from a technical standpoint but also just a reality of this world - politics decide things, not merit.

Politics trumping technical superiority being how things work should not mean that we accept politics trumping superiority. The only way this changes is with sufficient pushback. Unfortunately with web standards things have gotten so bad that I don't see any solution working out other than real anti-trust enforcement against Google.

There are plenty of use cases where image quality or coding speed cannot be compromised because of competitive reasons. For example medical imaging, professional or prosumer photography, legal evidence, printing cannot always accept small details disappearing or accept any other compression related degradations. JPEG XL, due to its better quality quarantees and great lossless options will surface in these areas first. Later, it will propagate from these uses to operating systems and eventually to browsers, too. Unfortunately slower transition puts some additional work on the web community.