I'm using Word. You do get more space if you type two spaces than if you type one. But that's not the comparison I'm making.

Here are the options:

A: period, one space B: other character, one space
C: period, two spaces D: other character, two spaces

You're saying that you get more space with C than with A, which I'm sure is true. But I'm saying that you get more space with A than with B. That at least is my understanding of the matter; I haven't tried to do a close comparison. In any case it's a different question, and it seems to me that it's the one that matters.