+1, not speaking for Google With large systems you want assurances at compile time, something that Python can't give you much of. When you have a huge system w

+1, not speaking for Google With large systems you want assurances at compile time, something that Python can't give you much of. When you have a huge system with many modules that interact in ways you can't expect anyone to map out without staring at a lot of code, it pays to have a stronger type system and fewer runtime errors. For experimentation and small-scale work, Python's great. Single client application? Fantastic (e.g Dropbox). Giant web service or distributed application? Starts to show its ugly sides quickly.