Sure, but most people who shouldn't have admin access do not have them already, (if the machine they use is managed). Even with Windows, if you are not in Admin

Sure, but most people who shouldn't have admin access do not have them already, (if the machine they use is managed). Even with Windows, if you are not in Administrators group, and your try something that requires UAC, tough luck, just like with sudo. That leaves us with private machines: should the user have the admin access, if it is his private machine? He is the owner after all. If "not yet", who and when will grant it, when the need arises/the user educates himself/etc? Also, how will the user, who is willing to educate himself able to do, when he is not allowed to try and fail? iOS turned this into a big brother scenario: there is someone else, who has to approve any program that you can run on the device. However, Apple might have objectives and responsibilities that may be different than yours, and they may deny you running an app, that is otherwise perfectly fine (and not just for technical reasons: imagine living in Crimea today, for example). Even on Android, there are things that you may legitimately want to do, but out of the box the system won't let you - you may either need the same signing key that the platform is signed with, or full blown root (backing up the device, for example). Both of these platforms take away possibilities in the name of what the mainstream user supposedly wants, and nobody is going to ask you, whether you are competent to use these features or not. Once you lose these possibilities, they are not going back.