The official installation path for Windows being Program Files is no different than the expected installation for the majority of .deb or .rpm files being /usr. In both cases, you can't install software with its default assumption as a unprivileged user. The defaults on both Windows and basically every Linux distribution assume software installs are done by a privileged account.
You can install to c:\Users\%USERNAME% if you want to, if the installer lets you pick a path, this is how Chrome installs. Just like you can install into ~/bin if you want to, but you are going to have to go a little out of your way to do it.