many non-slavery parliamentary societies have bicameral legislature, why do you think that is considering they never considered counting their slaves...?
Bicameralism appeared very, very early on. There’s a well known case of a missing pig in 1642’s Boston (with a population of less than 2000 at the time) that finally solidified splitting the assembly into two chambers, and that debate has been going on for a while at the time already https://www.americanantiquarian.org/sites/default/files/proc...
Non-proportionately? For example the Netherlands has a senate but the weight of senators per province is set by population. They don't let Saba have equal powers with Utrecht, which is exactly what the American system does. Other Anglosphere countries — all of which have exceptionally bad forms of government due to the legacy of England and the early influence of the United States Constitution — have upper houses that do not have America's weird geographic correspondece.
There is a particular sort of partisan who loathes any process, procedure, or rule that acts as an impediment to his agenda. Never mind that, quite often, these same processes, procedures, and rules often act as impediments to his opponents when they are (temporarily) in the majority, he sees his faction as ascendant forever because the universe is designed to promote his peculiar idea of progress and thus there is no longer any need for those hurdles and obstacles. In hushed whispers he might even confess he thinks there never was a need, that those were put in place by his enemies to thwart his righteous cause.
