Phones have just an image sensor with a direct interface to the CPU, with a driver plus a ton of software running on the CPU to enhance quality. You can get good cameras with modern image sensors with usb interface. Note that they need a local controller to well, control them and provide a usb interface, and need firmware for the local controller and need to provide a driver or support for a standard API at the USB end. The market is tiny compared to phones, so for those reasons you can't buy a usb camera with the same low cost and high performance as what is in your smartphone.
That being said, you can buy good usb cameras based on many modern image sensors from a company like e-con[1], but you have to do research about what features are enabled by the driver.
I'm not sure why actual webcams including a way to mount on your monitor are so far behind and expensive. Logitech C920 is still a common recommendation, and it's now 10 years old!
Phone cameras are very good but owing much of it to the DSP and software. An iPhone camera will not produce iPhone quality photos without the chipset and OS.
oh, that's for economic reasons. The industrial and desktop consumer computer vision markets are orders of magnitude smaller and their development cycle times orders of magnitude longer.
I looked into this a while ago- trying to use gcam technology for scientific imaging- when I worked at Google, and there was zero interest from those teams. They were 100% focused on next-gen camera tech (and it showed- that was the period when phones got unbelievably good at taking high quality images using computational photography).
