Why not using std::move everything?

i don't undertstand fully this answer. Why we not all using type with std::move?

Example;

std::map<int, int> try;

void foo(std::map<int, int>& try, int t1, int t2)
{
    try.emplace(std::move(t1), std::move(t2));
}

int main()
{
    int k = 1;
    int v = 5;

    try.emplace(k , v); // emplace copies
    foo(try, k, v); // emplace referance
    return 0;
}

so what is the different emplace copies and emplace referance? I know std::move more efficient than use copies. (if i know wrong, sorry. I'm beginner) So what can i use? Using copies or std::move? Sorry for my bad english.