The article's use of the "plain ol' developer position" phrase suggests that this person had a different problem. God forbid they said that in an interview... They were apparently not interviewing for jobs they actually wanted.
If you actually want the job, you'll be interested in it, you'll explain why you're a good fit, and you probably won't describe it as a "plain ol'" anything, even in jest, even to yourself. Otherwise, why waste the time?
This is true, at least in Einstein's case. Or, s/patent clerk/surfer/g, s/Einstein/Garrett Lisi/g But the romanticism has gone out of proportion.
I don't. PhD correlates with smartness, and smartness correlates with wages. Please take care not to assume causation.
But should you get a PhD just to make money without a love for research? Each year of industry experience at a young age will be more valuable to you than a year of study. Yes, you can get stuck. You can also get unstuck and learn ten different languages under ten different employers, as I did.
I would guess from your experience "building scientific instruments and software to control them" you would be able to find a job doing dev. If you can swing it while you're still a student, I would highly, highly recommend you do some internships with companies writing software, even if it is doing the same type of code you currently do. If you can't do that, pick up a minor in CS while doing your physics grad work.
FWIW, it sounds like the author here was really applying for the wrong job.