Simply put, python doesn't have any (non-terrible) built-in capacity for mapping HTTP requests to code like PHP does. At their core, python web frameworks are a

Simply put, python doesn't have any (non-terrible) built-in capacity for mapping HTTP requests to code like PHP does. At their core, python web frameworks are all about adding that capacity to the language. Full stack frameworks like Django go on to add a lot more, but the simpler frameworks are all about the request to code mapping, like bare PHP is. If you're intent on understanding 100% of your codebase, you should consider one of the single-file frameworks, like Bottle or Flask, and spend some time reading and understanding their code.