Few device manufacturers and platform ecosystems appear incentivized to bundle Firefox, perhaps because it doesn't provide much in the way of competitive moat-building opportunities in return for the partnership (there is the Google sponsorship, which is probably helpful in their unique case because it provides a defence against allegations of monopolistic behaviour).
The cost of bundling for Chrome and Safari is low, because it's software -- so they are included with a large number of devices, especially where commercial partnerships can be formed (generally on favourable terms to Google and Apple, respectively, I'd expect).
I don't think that the average user notices much difference in terms of behaviour and functionality between any of these browsers. I'll admit that there are probably rare exceptions like vendor-pushed codecs where one or other browser tends to have an advantage (again, typically leveraged by partnerships with streaming content providers).
So: I don't know, but it's something to do with getting Firefox on more devices by default -- and that's not something that happens easily when supply chains are easily influenced by a small number of upstream "ecosystem providers".
The cost of bundling for Chrome and Safari is low, because it's software -- so they are included with a large number of devices, especially where commercial partnerships can be formed (generally on favourable terms to Google and Apple, respectively, I'd expect).
I don't think that the average user notices much difference in terms of behaviour and functionality between any of these browsers. I'll admit that there are probably rare exceptions like vendor-pushed codecs where one or other browser tends to have an advantage (again, typically leveraged by partnerships with streaming content providers).
So: I don't know, but it's something to do with getting Firefox on more devices by default -- and that's not something that happens easily when supply chains are easily influenced by a small number of upstream "ecosystem providers".