There are many messages describing the pain of dynamic languages, but my subjective impression is that a lot of it is about poor quality code, rather than lack

There are many messages describing the pain of dynamic languages, but my subjective impression is that a lot of it is about poor quality code, rather than lack of static safety. Case in point: I wrote and maintain a mid-sized critical service at work, say 50k LOC or so. Yes, testing is an issue, you do find it's hard to test all branches etc, something statically typed would be a bit easier. But it's fine actually, well tested, well thought through, and refractors are fine. Meanwhile, my python service connects to a C++ service written by a contractor, which is absolutely awful and crashed all the time, or worse, produces totally incorrect results. No doubt it compiles though. One thing which is real is that barrier to entry to dynamically-typed languages is much lower and there is simply more crappy code around. Also these tend to be used by people who are programmers but not software engineers. Data scientist don't write prototypes in C++.