This is a complex question, but up front first and foremost in any Capitalist country, voting will always benefit the rich, even FDR style Social Democracy came about as concessions to prevent revolution in the context of a decimated working class and a rising USSR.

People, generally, vote along their class interests, but these are handled in a different manner depending on which country you are in. Using the US as an example, the DNC caters to social progressivism, while the GOP caters to social conservativism. On foreign policy, the GOP and DNC are near identical, and when it comes to domestic economic policy, the DNC caters slightly more to urban voters while the GOP caters to rural voters.

This is all, however, in the context of parties that function as businesses that sell policy to Capitalists. Both parties serve Capital, because Capital is what holds real power. It holds power over the media, the state, everything.

The answer to how to fix this is getting workers to organize. When workers organize, they raise their social and class awareness and can accomplish far more than atomized individuals can.