There is not a lot of documentation available about what's the difference between running a browser in WebDriver mode vs Headless so I did some digging...
Malicious users can intercept or monitor plaintext data transmitting across unencrypted networks, jeopardising the confidentiality of sensitive data in Drupal applications.
Automated accessibility tools are only one part of ensuring a website is accessible, but it is a very simple part that can catch a lot of really easy to fix issues.
Back in the Drupal 6 days, I built the BOM Weather Drupal module to pull down weather data from the Australian Bureau of Meteorology (BOM) site, and display it to users.
If you've ever patched Drupal core with Composer you may have noticed patched files can sometimes end up in the wrong place like core/core or core/b. Thankfully there's a quick fix to ensure the files make it into the correct location.