Just look, for instance, at FPGAs: almost all the tooling is proprietary, very expensive, and very buggy too. Or look at PCB design: Altium seems to be the standard here still, despite Kicad having made huge advances and by most accounts being as good or even better. It took decades (Kicad started in 1992) for the FOSS alternatives here to really catch on much, and only really because PCBs became cheap enough for hobbyists to design and construct their own (mainly because of Chinese PCB companies), and because CERN contributed some resources.
I'm not sure what the deal is with engineers hating collaboratively-developed and freely-available software, but it's a real thing in my experience. It's like someone told them that FOSS is "socialism" and they just reflexively dismiss or hate it.
Pure Software has a lot slack when it comes to delivering incomplete or (in the FOSS world ) even partially incorrect releases. Many issues can be fixed after the fact (even in production) and you can inch closer to a better version as time come goes on.
Mechanical engineering oftentimes can't work that way. An "80% solution machine" usually doesn't work at all and iteration costs (outside of 3d prototyping) can be staggeringly high.
Example: My company produces heavy "things" (20tons+) that have tight tolerances in some places. If the design is off by 2mm because of a CAD bug or unexpected/unknown UI the part could be scrap or require an expensive (read manual) rework.
There go all your software savings.
So why management would love to reduce the staggeringly high costs it's not worth the risk until an alternative is very proven.
In many projects customers contractually require is to use a specific solution.
The old meme from 10 years ago about: “Linux being free if your time is free” is largely false for personal usage, but in the corporate environment somebody will have to provide support and with the open source software this is going to be you.
People selling B2B software know that so they will usually price things in a way that it is just a bit cheaper to pay them rather then support and retrain staff.