It's hard to do when you have users counted in billions, and photos counted in trillions, and then have those photos stored across multiple datacenters and serv

It's hard to do when you have users counted in billions, and photos counted in trillions, and then have those photos stored across multiple datacenters and served globally through many CDN endpoints. It is undeniably possible, but the cost (money, performance) is so extreme and the benefits so small (the edge case of people sharing confidential things by copying file URLs when they are always going to be able to take a screenshot in an undetectable and sharable way)... that it just does not come out as a thing worth doing. Then when one considers that the faster you can make file serving and the UX of the web site and app, the more responsive and higher the engagement... which means increased likelihood to click adverts too. So you have a huge cost, with little benefit, vs a drop in speed and potential impact to advert revenue. No reasonable company is going to say that this should be done unless there is an overwhelming business reason to do so (i.e. you are Box and storing company secrets and the liability of leaking them is extreme).