Well we've only been a true "liberal democracy" for the past sixty years or so. Before that we were a de-facto apartheid state. Maybe at a stretch you could say 105 years if you go by the 19th amendment. And frankly i'm still skittish to call America pre-Trump a democracy with my full chest given the electoral college, completely bonkers division of the country into states, the senate, complete lack of a right to vote, our continual human rights abuses in terms of poverty and imprisonment/executions, etc etc.

I'm just saying there's literally dozens and dozens of countries with far more obvious realization of democratic ideals than we've ever managed to figure out, and at this point our age and blind devotion to dead assholes ("founding fathers") are major barriers to any sort of movement forward.