First, this is false. Policy in the US is dictated by campaign contributions, not voter sentiment.
Take a wildly popular idea, like universal background checks for firearm purchases. This enjoys something like 80-90% support among both Republican and Democratic voters, but it will never get through Congress, because of the NRA.
Second, "the people who elected them" is not itself representative of society as a whole. The US Senate and the US Presidency are decided by mechanisms that intentionally award oversized representation to certain geographical areas. There are only ten states with a population higher than Los Angeles County, but those states still get two Senators.
So American democracy is built to reflect the will of the monied, and the will of small population centers. Most of us are not rich, and most of us live in dense population centers. This means our system of government is giving us the exact opposite outcome we should be looking for.