Library / Internet Plug-ins folders- both empty (almost)

In searching the forum I've not been able to find even one question or discussion for this, which doesn't make a lot of sense, considering the seeming hugeness of it..?

In the Internet Plug-ins folder in the system Library there is only Google Earth Web Plug-in and nothing else, though when I use Terminal to show hidden folders another obscure tiny little file shows up there.

In the Internet Plug-ins folder in the Users Library (I'm the only user) there is absolutly nothing...

I discovered this while searching for some add-ons for Firefox that I want to get totally rid of... When I type about:plugins in the Firefox location bar I get a list of all add-ons etc., with the File and Path, and all of the paths indicate /Library/Internet Plug-Ins/(addon name) The only one that is actually there is as mentioned, the Google Earth Web plugin...

The Mozilla folder in the Applications Support folder of the system Library is also empty, in case there is a connection..? And in either case Is this not unusual..?

There is something essential for me I can only do with Firefox or I'd just get rid of it, except that there would still be all those add-ons lying about..?

I am also imagining that Safari's ectensions, add-ons, plugins etc would also be in the Internet Plug-ins folder, along with those that plug into or extend browsers in general..?

Again this seems so impossible considering that I cannot find anything on the apple forum about it....