Also vendor lock-in. The camera company gets no revenue from integrating with Google/Apple, and potentially loses a source of lock-in, so why do it?

Also, the RAW format that the camera stores is huge, and pretty much unusable. You'd want to store JPGs but those are export format not that actual image. Though I guess that's an answer to the lock-in question: export jpgs to the cloud, keep the RAW images on the device.