push_back() & emplace_back() relate to special member functions

[cwhii]

C++ Weekly - Ep 108 - Understanding emplace_back
https://www.youtube.com/watch?v=uwv1uvi1OTU

Jason Turner explains in a four minute video how push_back() &
emplace_back() relate to special member functions in C++. I am looking
for an explanation on how pure cpp2 improves/changes any of this.

#include <cstdio>
#include <vector>
struct S{
    S(int){ puts("S(int)");}
    S(){ puts("S()");}
    S(const S&){ puts("S(const S&)");}
    S(S&&){ puts("S(S&&)");}
    S &operator=(const S &){ puts("S &operator=(const S &)"); return *this;}
    S &operator=(S &){ puts("S &operator=(S &)"); return *this;}
    ~S(){ puts("~S()");} };
    
int main(){
    S s;
//    std::vector<S> vec;
//    vec.push_back(S());
//    vec.emplace_back();
//    vec.push_back(S(3));
//    vec.emplace_back(3); 
}

[gregmarr]

I would not expect any changes here, other than how the special member functions are spelled. What kind of improvements or changes would you be expecting to see?