why isn't Unicode the default encoding?

[John Salerno]

Robert Kern wrote:

> Well, *I* use UTF-8, but that's neither here nor there.

I see UTF-8 a lot, but this particular book also mentions that UTF-16 is 
the most common. Is that true?

>> Why can't Unicode replace them so we no longer need the 'u' 
>> prefix or the encoding tricks?
> 
> It would break a hell of a lot of code. Try using the -U command line argument
> to the Python interpreter. That makes unicode strings default.

I figured this might have something to do with it, but then again I 
thought that Unicode was created as a subset of ASCII and Latin-1 so 
that they would be compatible...but I guess it's never that easy. :)