I think the Dom/mes you have talked to who say it is impossible to do housework tasks are in error. Its not impossible to do housework tasks, what you are talking about is a difficulty in reporting on said tasks. You can assign the task, sub can do the task the problem you are talking about is proving it has been done. And that is not so much an impossibility but a difficulty.

Digital photos have been used in online tasking for a long time, ever since digicams became cheaper and widely available. Its certainly easier than the previous set up where photos had to be developed and with developing companies often reporting 'unusual' photos to the police this usually meant having to have your own dark room

BTW, to add to your thought, some camera phones have GPS in them and you can turn on a setting to implant the GPS co-ordinates into the photo data which means that someone who recieves the photo can, with the right software, see where the photo was taken (mine does it as an arrow in google maps)

For housework tasks I would say that video is also a good way to provide proof. You can set up a phone camera with a video setting and record a sequence of you doing the task, upload it to a computer and place it on a file sharing site for viewing. Far better than a photo.

Though, in my experience, sometimes the gathering of proof can get in the way of the task itself (I have spent ages trying to set up a camera correctly to record a task and have it not work and have to set it up again... its a pain). Also, it is very difficult to write a convincing report of a task you have not done - the feelings and experiences are sometimes difficult to fake and it is easy to make a mistake that reveals the lie.