Except that most typed languages are far faster than python. Retrofitting existing python projects with types makes sense for reliability, but starting a new project with python and types makes less sense, imo.
That said, if you care about the performance improvements that typing can give you with Mypy, you might want to look here:
https://github.com/mypyc/mypyc-benchmark-results/blob/master...
It won't be going toe to toe with Rust any time soon, but a 4x to 17x speedup is nothing to sneeze at.
Most of these things can be improved upon, but progress feels slow and there are so many other serious issues in the Python ecosystem (performance, package management, etc) that I've given up (after 15 years of daily use). It makes me sad, but Go and Rust seem to offer better tradeoffs for the things that I care about.
People use Python for its ease and speed of development, and extensive ecosystem. Things that need to be fast can have the appropriate effort expended to execute as fast as necessary.
Of these, I think only the ecosystem stands out anymore. For work purposes I wouldn't be able to move away from Python anytime soon, but if I could pick any language for new code it wouldn't be Python. If I had to pick the closest competitor, Julia seems like a great Python-like language in terms of speed and ease of development with much better typing and performance, but with a less extensive ecosystem. Nim might also fit that bill. If ecosystem was important, Go probably fills a similar space without being quite as steep of a learning curve as some of the other languages.
Well as a Perl fan I certainly don't disagree with that conclusion ;)
But yeah, you're definitely right that there's immense value to being able to quickly prototype.