Because it’s super complicated and a thousand moving parts are involved. You have to parse HTML, draw everything correctly, do JavaScript, Canvases, WASM, Websockets, HTTP 1.0, 1.1, 2.0, SPDY, support 10 different image formats, 5 audio, 5 video formats, allow videoconferencing, write a plug-in system. Handle Bookmarks, History, File downloads, uploads, … … …
The standards alone are thousands of pages. You gotta read them all, understand them and program everything. Which takes years for a team of developers. And you also want it secure or your users get in all sorts of trouble. A browser is the number 1 way to get malware on your computer. And all these experts take a decent salary. Multiply that (hourly) wage with multiple people and several years and you’ll end up with an expensive product.
And despite all that, if you don’t bend over to emulate Chrome’s quirks a ton of sites still won’t work properly and users won’t use your browser because the other one is more “compatible”. And you might still have to fake your user agent to be Chrome or Firefox so sites will even give you the fancy HTML instead of giving you the mobile or “limited” version meant for IE and older browsers.
I hate the fact that the only viable choice is between Chromium, Chromium, Chromium, Chromium, Chromium or Firefox.
There is Safari, which uses a different rendering engine, but yeah, there’s basically 3 browsers. Chromium, Safari, and Firefox.
I don’t use Safari and never have, so I can’t speak to its compatibility or quirks for the user or for developers.
