What is the rationale behind std::bind and std::thread always copying arguments?

Question

It\'s pretty well known that the default behaviour of std::bind and std::thread is that it will copy (or move) the arguments passed to it, and to use reference semantics we will

Answer 1

std::bind creates a callable which is detached from the call site of std::bind, thus it makes much sense to capture all arguments by value by default.

The general use case is to be identical to passing a function pointer to a function without knowing where it might end up.

Lambdas give more flexibility for the programmer to decide whether the lambda will live beyond the scope arguments are captured from.