A lot of university programs in my field are now teaching Python instead of Matlab and the professors are developing libraries. When their students get jobs and budgets for the first time, they buy tools and the Python gets relegated to being an occasional supplement.
This isn't just Matlab vs Python. Most people do work that doesn't look like software engineering, even when they use software tools. They have other needs that need to be met.
And if you look at the total cost of closing the gap between Python and something with a license fee, a lot of times that "expensive" license starts looking like a pretty good deal.
You're trying to tell people with different jobs than you to work like a software engineer because you're ideologically opposed to something that looks like a programming language costing money. It doesn't make sense.
That's what confuses software engineers about Matlab. They see code and think that the work is software engineering, but that's not always the case.
Imagine the reverse scenario. The professor sees you crunching numbers in Python and tries to convince you to switch to Matlab because it's "better". But you're a software engineer, and you still have to do all your software things that Matlab isn't great for. Why would you be interested in it?
Some people in teaching roles will even further Matlab's spread irresponsibly out of not wanting to learn a new tool. I have seen this myself. A professor showed the students Matlab, instead of using non-proprietary alternatives. He also did not seem interested in learning about anything else, when I used Python + Numpy instead and showed him.