There is no issue with SketchUcation's AutoInstallers !
IF there are additional folder-paths found in the $LOAD_PATH - either because Fredo's AdditionalPlugisnFolder tool has added them OR because the 'shared' C:/ProgramData../Plugins exists - then these locations are offered as alternative destinations for an SCF AutoInstall [with the User's Plugins folder as the first one listed] - unlike the native Preferences > Extensions > Install which is always into the User's Plugins folder.
To reiterate...
The C:/ProgramData../Plugins folder is for use when a computer is to use a 'shared' Plugin or Plugins. Such Plugins are then auto-loaded as SketchUp starts for every user on that computer.
The default installation location is into the User's Plugins folder - this means that each Plugin a user installs into that folder is only auto-loaded as SketchUp starts for that user.
Many users will not want or need a second 'shared' Plugins folder.
Even if there is more than one SketchUp user on that computer they may well prefer to keep their own 'User' Plugins separately.
Having a shared Plugins folder when it is not wanted/needed imposes unnecessary complexity on a user.
If your installer bulldozes across a user's current setup and creates a new 'shared' Plugins folder, then it stands to reason that they might not be happy about it.
Automatically creating it and changing things without asking is not a responsible approach [IMHO].
If that shared Plugins folder already exists then there is possibly not change to their arrangements... but even if the shared Plugins folder does already exist, then your automatic installation of things into it is contrary to the normal installation of Plugins, which always auto-install with Preferences > Extensions > Install into the User's Plugins folder, or with the SCF AutoInstallers you are given the choice of folder, defaulting to the User's Plugins folder.
After all, the user might not want to share your plugin will all of the other users on that computer: even if the shared Plugins folder is preexisting it is no indicator of the user's desires.
So I think your installer should offer two installation destinations:
User's Plugins folder
Shared Plugins folder
If the shared folder doesn't exist, then in fairness you ought to warn that creating a shared folder might affect some aspects of future installations...
This approach seems common-sense to me ๐
Why do you want to go against the tide โ