I'm not a lawyer, but I'm not sure they've got things quite right in their article.
In the U.S., copyright lasts the life of the author plus 70 years for works first published on or after January 1, 1978. Before that date, copyright terms lasted fixed periods of years.
For works first published in the U.S. between 1923 and 1964, the copyright term was 28 years and renewal granted an additional 47 years. That was extended to 67 years in 1998, but only for works that hadn't already expired. I think the 28 years plus 47 years is where Vice is getting their 75 year number. But, that's based on when the work was published and it doesn't matter when the author died.
So, works first published in the U.S. in 1924 should have gone into the public domain in 1999, but Congress passed an act in 1998 putting it off for another twenty years.
Works first published between 1923 and 1963 in the U.S. are in the public domain in the U.S. if they were not renewed on time. That's often difficult to determine, which is why the 95 years becomes the magic number, because if they were renewed on time, the maximum period of time those works would be under copyright protection in the U.S. is 95 years.
Bottom line is that, for those works, you needn't worry about when the author died.
For works first published outside the U.S., it gets more complicated. You also need to be careful of situations where something might be public domain in the U.S. but still under copyright protection elsewhere in the world, especially if you're using it in some way and are publishing your work outside the U.S.
Again, though, I'm not a lawyer.