Why is it so hard to get headshots in this game while opponents seem to have no problem with that?

To make those 20 headshots it took me more than 15 matches. Most of the matches had no headshots at all. I hit the head 1, 2, 3 times, but when I hit the shoulder and make the kill it with that shoulder-hit then it's not counting as headshot anymore? This is so frustrating.

https://steamcommunity.com/sharedfiles/filedetails/?id=3774504636
But somehow opponents seem to have no problems to give me instant 3 to 4 headshots in less than 10 milliseconds from a distance of more than 70+ meters. The game constantly makes you feel like you're the biggest loser on the planet...