Perhaps a good C++ programmer writes equivalent code in C++ just as fast as he would in Python (For some kind of tasks I've found this to be true as well), but

Perhaps a good C++ programmer writes equivalent code in C++ just as fast as he would in Python (For some kind of tasks I've found this to be true as well), but how many good C++ programmers are there? It's a brutally tricky language and getting quick requires knowing how to avoid the sometimes subtle pitfalls. I suspect that for the vast majority of web apps though, PHP, C#, Rails, whatever is 'good enough' and they run into the db as a bottleneck if anything and would rather scale out their scripting layer with more machines. The framework ecosystem around C++ as a web app language also isn't as rich, so it requires more work to get started.