Every is talking about how the headrest it's made this way for crash safety when it's blatantly untrue.
The headrest is designed to protect the heads and neck of the average man, not woman. Decades of crash test dummies have all been modeled on the average height and weight of the male body. This is why women are 47% likelier to sustain a serious injury in a crash.
Think of the where the headrest is in the optimal position to protect the driver, and then move that a few inches lower. Adjustable headrest often doesn't even go low enough to accommodate for many women. There is an actual cutoff height where you are just screwed and expected to die more. Not to mention the user error of forgetting to adjust the headrest from the factory setting of accommodating to the average male height.
This is why so many people are curled up like a shrimp. They are either: short, a woman, or the statistically deadliest of all, both.
Oh it's 'blatantly' true that the headrest are for safety. The problem is engineers can't design a perfect one size fits all. So things are designed around averages. It's the best they can do.
If you fall outside of those averages at either end well, there is going to be more risk. As a male who is above average height, automotive headrests add more risk for me just as they do for a smaller woman.
But they can make a headrests that do that. My car's headrests can tilt forward or back depending on your preference. And it was made in the 2010's, so it's not like this is a super old, or new, development.
Making them adjustable makes the most sense as it allows people to adjust it to what they need, rather than just designing for the average person. The seats themselves are adjustable; you can slide them forward and back, up and down, some even tilt them forward or back. The headrests should be no different.
Then design one that passes all the required testing and market it. Just because it seems easy doesn't mean that it IS easy. And your old car was quite possibly built under different guidelines. Meaning that they no longer meet safety standards.
While I definitely think there's truth in what you say, I don't think it's the real reason. The posture car seats try to put you in is just not good sometimes. If the seat itself lets you sit up straight, the headrest juts out, or the headrest is okay but the seat is curved into a bowl. It's comfy for lazy sitting, which is what most people will want to settle into, but if you try to be mindful of your posture, you're doing it without real support from your seat.
They really aren't primarily head rests, so comfort isn't the priority and my car's manual doesnt call them that.They're first and foremost head support for accidents.