Anecdotal: I'm a part-time CTO (long story) of a startup. I'm 30 myself. We hired 6 engineers in total up until now: three interns in their twenties, who're very smart and motivated but also inexperienced; two programmers with a few years of professional experience who can get to real decent (well written, unit tested, etc) code on the first go; and 1 guy of over 40. When hiring, I was very skeptical of the guy over…
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In fact none of the sentences you list are real evidence of discrimination, especially in the context of a discussion where it's necessary to separate candidates or hires into categories based on age/sex/religion/etc.
I was skeptical of the guy from China... because we was unable to answer any of the technical questions we asked him during the interview.
You'll note that the parent did not specifically say his skepticism was due to age. Instead he listed standard employment history features that are more common among older programmers.