We elect people based on ideology and character. They may have a few central policy platforms, but there are so many laws and resolutions passed that they cannot pre-advertise their positions or poll their constituents for every one.
Hence, why we are a republic (or representative democracy, if you will). We elect people on the basis of trusting they will do the right thing, because noone has the time to track municipality, state and federal votes.
Among the many experiments on local organization early communist China had was essentially a pure democracy (for local matters), and the inevitable result was there were so many votes that people were overwhelmed and disengaged.