That's one reason I mentioned pass by reference "smart" languages will do it automatically depending on the size of the argument, some languages (including my beloved PHP) even have a copy-on-edit functionality where everything is technically passed as a mutable reference but as soon as you mutate it (unless it was explicitly marked as a mutable reference) it will copy the original object and have you edit the copy instead of the original.

Is being explicit about when copies happen almost always a good thing - yea the overhead of that system is undesirable in performance sensitive situations - but for a high level scripting language it's quite nice.