Take a lot of craft trades. Ie, wood working, painting, music, writing, whatever. Those can often be people who just love doing the area, they love creating with their medium. I feel passionate tech people are similar.
The example of a medical professional was.. unfair. Yes, free time usage as a measuring stick for passion in some fields (like medical) is a terrible measuring stick, but I'm not legally inhibited from wood working in my free time.
Note that I'm not at all speaking about whether you should be binary about hiring (passionate people vs non-passionate). I'm simply talking about how in some crafts, crafting outside of work-time is a decent indicator to passion. Another indicator is, I feel, knowledge outside of their professional experience. I'm not a frontend programmer, but I enjoy learning and following tech trends, so I've used and can speak somewhat comfortably with frontend frameworks, my preferences in them, and etc.
There are other areas where "engineer" is thrown around pretty liberally as well in the US. But title inflation in software is probably more pronounced than just about anywhere else.
At ten years you should be absolutely expert in the areas you've worked in. This is staff or senior staff level, if you also have some business acumen, ie the ability to see beyond engineering requirements.
(In STEM. Obviously you presumably don't apply to Juilliard because you decided you might want to give this music thing a try.)