Most tablets do not have sd card or usb sockets that can be used to transfer files from a camera. If you use a desktop or a laptop, it is much easier to remove the card and drag and drop the pictures into a folder on your computer.
However, if you are out and want to share a quality picture taken with a decent camera then wifi works perfectly well. The app usually allows you to reduce the size of the image to save data space when transferring social media.
I have a Nikon SLR with wifi and WMU on my android and iPad. Works well and I do no think it will be long before we see this even on the cheapest digital cameras.
You can also the app to take pictures by remote - cannot change the focal length on mine as it has manual zoom, but some can if they are motorised.