I would guess because bitterness is what makes it taste like an "adult" drink. A lot of non-alcoholic options tend to be sweet: soft drinks, fruit juices, mock

I would guess because bitterness is what makes it taste like an "adult" drink. A lot of non-alcoholic options tend to be sweet: soft drinks, fruit juices, mocktails being the first that come to mind. The newer trend with companies like seedlip, or with actually good non-alcoholic beers means you can having something "adult" to drink without rotting your teeth