Those are still mostly scientific domains, and science has been rooted in open source. Most mechanical and civil engineering, on the other hand, is done in Matlab scripts and proprietary simulation frameworks. Matlab is Wolfram’s chief competitor, not Julia, R, or Sage.
Yea, AutoCAD is huge for Civil Engineers and Matlab is also pretty big for many engineering students, academics, and research professionals. I think most of the heavier users in industry used it all through grad school and then brought it over into industry. Most of us engineers that just have a bachelor's degree weren't as firmly rooted in Matlab and just picked up Python as our first post academic language. Both are good. Matlab has some advantages like bundling suitesparse (world class linear algebra subroutines)and handling the license of that so you don't have to get one yourself (assuming you want to sell your product).
I think Python definitely wins as a scripting language lingua franca though. It is free as in beer, open-source, available on any OS I care about, and most of the software I use has a built-in Python API.
Mathematica is big in academic math and physics programs, but I haven't seen it in industry as much as Matlab. Believe it or not, my company had a major accounting application written in Mathematica, so it does pop up in weird places.
