There's no other reasonable way for Python to work here. It *is* an error to pass something that's not a callable as a thread "target", but it's a coding error that can only be detected at runtime, not a syntax error that can be detected statically before the code executes.

And because threadFunc() never returns, Python never gets the opportunity to check the arguments to threading.Thread: the arguments to a function call have to be evaluated before that function call can be made.

It is a fairly common error, though, and it might be possible for a linter to flag this error (though probably with a smattering of false positives and false negatives). That's out of scope for Python itself.