There are other indentation-sensitive languages that do care about indentation of nested sub-expressions. The key issue with Python is that it disregards all indentation that's inside parenthesis or brackets.

The C specification does specify the nearest-if rule, so that all compilers will do the same thing with unbraced if-else. However, the real problem is that it's more confusing for programmers. The programmer might be thinking of the second option, but the compiler will actually do the first one.

Usually it's a big enough number (e.g. Lua has 256 registers)

For Haskell, the laziness is probably more important than the purity when it comes to IR design. It doesn't have the usual notions of "control flow".

In Python, the dangling else problem is avoided by significant indentation, which is analogous to mandating braces around the if/else body. Python's elif allows if-else-if without having to nest the elses in increasingly deeper levels of indentation (which would be analogous to the }}} problem discussed in my answer).