At home you have all of the privacy you need without someone looking over your shoulders at what you are doing. Also you will not have the problem of someone monitoring what you all looking at. But at work you will have someone who will monitor what you are watching and doing. Also you will not have too much privacy because people are always walking around and coming Into your office now and then to see what you are working on.
In public setting you have a good chance of someone looking at what you are doing more often. You also would not have easy access to where you would have some privacy to do your web browsing. A library computer lab everybody would be using it and someone can be waiting on you to get on It as will. This place will surely have people that are always walking around being noisy trying to see what you are doing. The basis that I look for is to make sure that no one can steal any of my information that I would be using say buying something Off web site.
That something like a metal sheet is put up so no one can clone my computer. No it is not legal because this would be the same as you stealing from someone. As of right now there are no certain laws that are available to stop someone from using other people wireless signal. Yes, it is ethical because you know that it is wrong but you choose to do it anyway. How would you Like it if someone was doing this toy and you know It and you are the one paying for It how would you feel?