Python 2 and 3 are not compatible via syntax translation in the same way that many new JS features can be transpiled to old JS. In Python 3, strings work differ

Python 2 and 3 are not compatible via syntax translation in the same way that many new JS features can be transpiled to old JS. In Python 3, strings work differently in subtle ways that force you to be more careful, and a source code translator doesn't have any reasonable way to know whether a variable is a string anyway. You also see this sort of thing in JS: Babel never tried to implement Proxy because it really needs runtime support and can't be implemented by syntax translation.