The problem you're describing isn't a lack of interest in facing cross platform/browser challenges, but rather substantial barriers to entry preventing develope

The problem you're describing isn't a lack of interest in facing cross platform/browser challenges, but rather substantial barriers to entry preventing developers from doing their job. To test on Safari, you need a mac. That is a substantial cost. We assume it doesn't exist because we work at places that offer us macbooks (of note, all my teammates test on Safari because we easily can now), but when we are talking about the web at large this is a tremendous cost and is why so many websites are broken on Safari-exclusively (as opposed to both Safari and Firefox). So many websites, even from large companies, are developed by a handful of people, and their habits carry over. This establishes an expectation of not caring about Safari and all of its quirks, it gets relegated to "the user will just use another browser if it's broken". For this problem to cease existing, Safari needs to be released on other operating systems. Until then, Safari will always be disregarded and untested.