Look at SOPA/PIPA. They simultaneously pushed the same bill through both chambers to try and guarantee it would pass. Grassroots efforts led to it being overwhelmingly blocked in both cases. And then they just slowly slipped most of it's provisions through other legislation over the years.
Except for a few types of bills that customarily originate in the house, most bills are introduced roughly simultaneously in both houses so that the information for debating the bill doesn't have to be brought twice. This obviously doesn't guarantee a bill will pass because it is required to pass both houses.
I think we should be at least several decades past looking at the USA as a particularly functional democratic system...
The US constitution, despite its biblical status in their culture, manages to be more of a distracting throw-word ("LOOK at how this bill helping provide healthcare OBSTRUCTS your CONSTITUTIONAL RIGHT to NOT CARE ABOUT THE POOR!" (Ok, not a great example)) than a functional constitution that limits institutional overreach.