I think one difference is that for many languages like Python, the http endpoints are hosted in one process. That's less horizontally scalable than lambda services.
Having said that, this is actually irrelevant when trying to scale out. There's nothing that prevents you from starting your application multiple times each copy on a different machine. As long as your application is stateless (which is a requirement no matter which language you use). I don't think there's any programing language which prevents you from doing that.
[1] http://uwsgi-docs.readthedocs.io/en/latest/WSGIquickstart.ht...