- Python (like most other scripting languages) does not require variables to be declared, as (let (x 123) ...) in Lisp or int x = 123 in C/C++. This means that Python can't even detect a trivial typo - it will produce a program, which will continue working for hours until it reaches the typo - THEN go boom and you lost all unsaved data. Local and global scopes are unintuitive. Having variables leak after a for-loop can definitely be confusing. Worse, binding of loop indices can be very confusing; e.g. "for a in list: result.append(lambda: fcn(a))" probably won't do what you think it would. Why nonlocal/global/auto-local scope nonsense?
- Python has a faulty package system. Type time.sleep=4 instead of time.sleep(4) and you just destroyed the system-wide sleep function with a trivial typo. Now consider accidentally assigning some method to time.sleep, and you won't even get a runtime error - just very hard to trace behavior. And sleep is only one example, it's just as easy to override ANYTHING.