This is because for the most part, the browsers listed above are all built on different platforms, meaning that developers who create an extension for Chrome can’t assume that their extension will work for Safari or Firefox. In this case, Chrome and Edge are built on Chromium so extensions built for either browser should be available and will be compatible with each other.
As for the other browsers, your mileage may vary depending on the extension and whether or not the developer has bothered to create an extension for your browser of choice.