Rather than me explain it best just to watch this short video. The one he has is the commercial version which cost $150. You can put one together for under $20, works exactly the same, as I stated above the software needed is opentrack software and its open source.
Yes, I know how they work and that video highlights many of the things I was saying. Without a display that covers your FOV, you're going to end up doing weird strained looks where you're turning away from the display as part of it, so its something that I think seems more immersive but has glaring flaws that makes it less immersive for me because the scaling isn't quite right and you have to be aware of your own space (which isn't the same as the space you're in in the game (well unless you put in a ton of effort to make it that way). Kinda like the Wii's controllers, they sound good in theory, but in practice it just didn't work as well and became tedious pantomime that reduces the immersion for various reasons.
Now, with a full cockpit setup, or VR and other things, that makes a bit more sense. For a single typical computer monitor, you're going to be looking away and doing a lot of awkward movements with your head to enable the changes you see on the screen (and you're going to make some of that pointless as your awkward head movement makes the screen less visible). For me, that actually hurts immersion more than it helps it. I'd rather focus the view on where I'd have my view focused if I were actually there (and flying a plane like that, or driving, its on the sky or road, not on the immediate cockpit for most of the time I'm there; they spend a lot of time trying to make controlling things intuitive so that you're not sitting there fiddling at all the different controls, or for flying bigger complex jets you'd have a lot of tr
I know some people like that, and like I said, its a neat project, but it just doesn't work for me, it basically makes me constantly aware of the hardware outside of the game, but for a single monitor it just reinforces that I'm playing a game and watching things through this little 2D window, keeping me from losing myself in the immersion of the experience. My mind actually immerses more when I'm not thinking about all the hardware and are using a simple intuitive controller so that I focus on what I want to actually focus on.
Again, I'm not saying its worthless, and I know people that do a lot of stuff like this paired with doing more (multiple displays or VR headsets, flight controls, even building their own little simulator thing that actually resembles real cockpits - well as much as you can while not spending a ridiculous amount of money) to heighten the immersion, and that the DIY aspect is appealing (to me that's the most appealing aspect).
Oh, and another point, in real life I can keep my eyes focused while changing my head quite a bit, but using that it's gonna be changing my view quite a lot. I know they're moving towards eye tracking for VR as well to make it so you can do that (although I think some of that is actually basically just shifting all the tilting so that the info is provided by your eyes and not your full head movement).
Its kinda the old, give a kid a cardboard box and they'll have more fun and immerse in their imagination than a toy that seems really immersive or "realistic" but has flaws. It often burst the immersion bubble and then you become aware of and focused on the aspects of it compared to your mind fully in its own space. So we keep adding things here and there that will help the overall immersion once we get things right, but it can also hurt the immersion because we're dealing with the not fully formed (or "there yet") implementation of it. I'm not trying to criticize that, just recognize why it can often feel less immersive than playing some simple yet incredibly bizarre game (like Mario Bros, I can become more absorbed into something like that than I can many of the sims because of how I'm able to focus on what is there with the former versus what isn't there in the latter).
I actually thought the way that the one guy reversed the IR tracking on the Wii was more interesting (the one where he had the IR trackers on some glasses, and he had some targets that when facing straight on appeared to be flat on the same plane, but then he'd step/walk in different directions and you'd see that some were closer and others farther away). Stuff like that is fun, but the stationary cockpit type stuff really just takes me out of the game for some reason. I know that's not true for everyone though. Its kinda weird in that I remember liking the cockpit view when playing some racing games (the first Xbox 360 Project Gotham Racing game comes to mind as one I enjoyed), but often times it doesn't (like the ones where you see the top of the dash and steering wheel, maybe the speedo, even though that's probably more realistic, it often was less immersive to me because there was some weird awkward disconnect happening). But I always preferred the behind the car view over the "bumper barely off the road car POV" view (but know that some people apparently feel the complete opposite and wonder why anyone would play a racing game from not the most first-person view that you can).