Then shows a table of numbers that are not aligned to the right with the same number of digits.
25.5
19
78.2
Better still to avoid tables, and use charts instead, which the author mentions a couple different ways.
But there's lots of good advice here, it's not really fair to question the validity of the entire article just because it left out one minor thing that you care about.
Column alignment is pretty subjective (and again, I think the chosen one looks more pleasant than what you're proposing), what the writer was getting at was making sure that the point you'd like to get across is being highlighted in someway, hence the red column amongst the black.
No, there's absolutely nothing subjective about this topic. It's objectively easier to compare numbers and see differences when they all have the same number of digits AND are aligned to the right.
9
90
8,0
2
89
9
90
8
2
89