Comment by lmm

Digital cameras have a stable(ish) lens interface, so people use a smaller number of models for longer. Consumer inkjet printers are so cheap and change so often that there is no single model that's popular enough for people to coalesce around (and people who do care about e.g. a printer that works well on Linux will research and buy one that's known to work well on Linux - printers are pretty much a commodity, whereas people have strong feelings about their camera hardware and want to use a particular camera with different firmware instead of changing cameras)