sort the entire line contains blank?

Question

There are 3 lines in aaa.txt. The first line contains space(ASCII 32), the second line contains tab(ASCII 9), the third line starts with space.

2 3
2       4
 2 5

Then type sort aaa.txt. GNU manual said If no key fields are specified, sort uses a default key of the entire line. Because tab is less than space, so the right answer should be

 2 5
2       4
2 3

But my bash shell got

2 3
2       4
 2 5

Questions:

1. Why the actual result is different from theory result? Does the separator not participate in sorting?

2. Blank is the default separator. So space and tab are separator in the same time? sort -k2,2 aaa.txt should get the theoretical output below because 3 < 4 < 5?

   2 3
   2       4
    2 5