Why would someone make a language where the programmer and the interpreter have two different ways of figuring out where blocks start and end?

To weed out programmers who don't indent.

Like with array base indexes, there are plenty of languages that start with something other than zero, and many that use indentation, including a few well known in hacker circles, Python isn't alone.

I never understood this.

What kind of special whitespace requirements do people have?

It's really not that bad