There's no mechanism for pressing politicians except threatening not to vote for them again, and politicians are exceptionally cowardly and avoid picking up hot potatoes that could incur criticism. I'm in a district with one of the safest seats in the country, and getting my representative to state a position on many issues is like getting blood out of a stone.

There's no formal mechanism of accountability for members of Congress. Representatives hold a few town halls a year where they might be subject to social shaming by their constituents, but there's no legal obligation to do so and even when they're publicly embarrassed they often dismiss public opposition as 'a few paid agitators' or the like.

This is doubly and triply true for complex policy issues which require a lot of explaining, making it virtually impossible to build grassroots support. So you just end up with a nonprofit industrial complex that needs to constantly raise funds for lobbying and publishes slates of endorsements at election time that relatively few people have the time or inclination to read.