When I said "the US can't even agree," I was thinking more about political institutions, not "we the people." The proposed Equal Rights Amendment to the U.S. Constitution has been ratified by 38 states, which meets the minimum according to the process for amendment laid out within the Constitution itself. The main excuse for not adding the ERA seems to be that it took about a hundred years to get these ratifications, and the later ones supposedly missed a deadline. To me, however, that seems more a problem of bureaucracy than democracy. More significantly, it shows a lack of political will at higher levels of (non-)leadership.

The other thing I meant is that there's a meta-problem of whose voices are heard. The ERA would ban sex discrimination. Such a basic precept seems a prerequisite for having a democracy in which women participate. It's famously difficult to pursue equality using tools that were not designed to produce it. If a constitution is written for men, there will be reasons-and-excuses why it shouldn't be amended to include women, including that women have been trying for too many decades, so let's restart the clock and make them begin from the beginning, which as far as I've heard is the main "argument" against adding the ERA right now, when considering that a sufficient number of states have already ratified it.