How can one of the richest men in the world eat peanut-butter-and-jelly sandwiches, as Bill Gates did while being interviewed for My Next Guest Needs No Introduction with David Letterman? Shouldn't he be eating something with truffle oil, or caviar? To me, Apple having the highest market value of any company doesn't seem like it should be related to the quality of their free web browser at all. I've never heard them answer a question about Safari with "we don't have the money for that," which would make the relationship relevant.
It seems like the same sort of reasoning as: "Apple is the richest company in the world and their company sweatshirts aren't even as good as this sweatshirt company's?" I mean, yeah, a company devoted to the sole purpose of a single thing, with no shareholders even, should expect to be number one at that single thing. I guess it's pretty embarrassing for the Firefox team that they're considered a number two to Google.
As I said in my first comment, Apple disagrees with some others on what should and shouldn't be in a web browser. They haven't implemented push notification because they disagree with their inclusion, not because they can't afford to do it.
> Apple only started properly funding Safari and catching up with Firefox and Chrome when regulators started looking into their practices.
I'm not sure what you're basing this on. Safari was the first browser to achieve 100% Acid3 compliance back in 2008, which was a thing they seemed to care about more than anyone else, although the rest of the browsers caught up soon after. Again, and it doesn't seem I can say this enough: Apple has different priorities than Google or Mozilla do. Those priorities change over time, which might lead you to think they're either pulling ahead of falling behind in the areas on which you're focusing, but they've been pretty steadily developing Safari while keeping memory usage and energy usage low and avoiding what they see as security pitfalls.
They don't deliver the same PWA functionality that Chrome does on purpose, not due to lack of funds or effort.