Most software installers demand to be run as root/Administrator.

The fact that this is largely seen as acceptable or even sensible is rather silly in this day and age.

Yes, and when apps do request many permissios, I just estimate how reputable the company is. A name like Adobe must be ok, right?

>Yes, and when apps do request many permissios

Most windows apps aren't sandboxed so the concept of "permissions" doesn't make any sense. The most there is is "asks to run as admin", but most installers do.

Software installers need Administrator privileges to edit C:\Program Files\. But once they get the permission, you can't really tell if they are "genuine", or if they also edit C:\Windows\ or messing around the registry.

It is just a really bad design without built-in sandboxing.

Software wants to be installed in C:\Program Files so that other software can’t modify their installation without admin permissions. Of course to do that your installer needs to be run as administrator which makes the whole thing rather silly.

The fundamental issue is that installers shouldn’t exist

There’s no need to have an executable program just to essentially unzip some files to disk

>There’s no need to have an executable program just to essentially unzip some files to disk

What if you need to install some registry keys? What about installing shared dependencies (redistributables)? What if you want granny to install your app and left to her own devices, it'll end up in some random folder in the downloads folder?

Software installed through the Windows Store seem immutable enough even though they live in the user's AppData.

At least the system prevented me from seeing or modifying the files the last time I tried. I did not try very hard, admittedly, but by contrast modifying something in C:\Program Files is just one UAC confirmation away.