Developers for the linux kernel are getting paid, and getting paid very well (I'm betting many closed source devs are wishing they would have gone the open source route!), look at the names of the maintainers, most of them are people with a good position at Intel, IBM, RedHat, Novell, universities, research institutions, etc... and linux kernel people are hardware people, they don't even touch userspace, they make sure the linux kernel, which is by far the most used kernel on the planet, infinitely more used than any other kernel, is compatible with as many hardware as possible. This is done by submitting code to be integrated into the kernel, not by making separate drivers. The ONLY and RARE exceptions to this rule are SOME CONSUMER GRADE hardware parts, mostly "gaming" parts, like certain graphics cards, "gaming" input devices, cheapest tier consumer grade inkjet printers or multifunctionals, and pretty much everything from the consumer product range by nVidia and Canon. This is because of Microsoft license deals mainly and because of old fashioned market protectionist policies, while even technologies that are basically touching EAR rules (open source cannot feasibly be subject to EAR, of which the main chunk was encryption technologies, which are classified in the US as "munitions" since WWII, but since the early 1990's, open source encryption technologies have become the prevalent standard, and the whole restrictions debate has become pretty useless for mass market products), like GPU acceleration functionality that is optimised for encryption/decryption functionality, or encryption accelerating CPU technology, is just as well supported by the linux kernel as technologies not touched by EAR. Some WiFi chip manufacturers however, have refused to provide headers and/or driver code for some Wi-Fi chip models that were mainly made for consumer devices because of economic reasons. Instead of submitting code, they have opted for developing new chips and submitting the code for those, because the technology evolved very quickly in the 2000's, and they needed more resources to develop new chips than to make linux drivers for older chips, and most of these affected chips were pretty unstable, like you said, and had already cost much more than anticipated just to be able to make the windows drivers work. In the mean time though, most older chips are also supported by the linux kernel, through the use of firmware packages, and there are very few exceptions. It took a long time for manufacturers to see that linux is not only for business use. Even Asus will be releasing its first ever mass produced line of laptops with Ubuntu preloaded instead of Windows this month, for 100 USD less. The linux kernel supports infinitely more hardware than Windows. And it has done that for a very long time. I don't know where the misconception comes from that the linux kernel is less hardware compatible than Windows, because it obviously isn't, most hardware is natively compatibel with the linux kernel, without need for a separate "driver application" like in Windows. The Windows kernel is in fact only compatible with a very short list of hardware, and needs externel drivers for pretty much everything, including elemental things like USB ports, etc.., notwithstanding the fact that the windows kernel is several times larger than the linux kernel. The linux kernel only needs external drivers for graphics cards and printers, and some isolated older consumer hardware items. Even exotic things like controllers for industrial robotics, sattelite systems, etc... are all natively supported by the linux kernel. It will be hard to even find stuff that can be hooked up to a computer (and not only an x86 computer, but any platform), and that is not natively supported by the linux kernel.
I don't quite understand your last paragraph, I don't see what you mean.