“But it isn’t getting picked up because of a penalty. It is simply a practical decision on the part of the SE’s to not use spidering time on duplicate content.”

It should say:

But it isn’t NOT getting picked up because of a penalty. It is simply a practical decision on the part of the SE’s to not use spidering time on duplicate content.

Re. Duplicate content, one of the so-called “penalities” for duplicate content isn’t actually a penalty, though functionally it can come out that way. It has to do with how often a site is spidered.

One SE did research on how often duplicated pages are changed. They found that after 10 weeks, the duplicate content hadn’t changed. So rather than waste indexing bandwith, they choose to spider one of the duplicate sites significantly less often.

That explains why the multiple sites (noted in your article) with duplicate content could all rank high: the “penalty” for duplicate content often is simply being spidered less often. But if your page remains the most relevant in its vector scores for the query in question, you can remain ranked high indefinitely and without a so-called “penalty.”

However, if you change your content, and you aren’t spidered at all for a time, because your URL is on the “duplicate” list, it can feel like a penalty because your new content isn’t getting picked up. But it isn’t getting picked up because of a penalty. It is simply a practical decision on the part of the SE’s to not use spidering time on duplicate content.