See first attachment - those on the right were downloaded and installed by me as a result of something such as you see at the bottom of this page ==>>
Link Shell Extension. None of them were automatically installed by other programs.
Two of the applications I previously mentioned use python, calibre and GIMP and yes they install the python they need in their install directory. Not sure about Photoshop it's not installed on this machine but I think most plugins ship as DLL's and are written in C++ with a few in Delphi and C. FPV, Irfanview, and NP++ plugins ship as DLL's, so I would guess they're written in C++ or C.
I get twitchy when application packages install '3rd Party' software, especially if its into the Windows directory without a) asking for my permission, b) asking me to agree to the license conditions. And particularly when it's a discrete un-installable item that I wouldn't even have noticed being installed had I taken my eye off the install.
BR