Well for starters there is a fee to present yourself to an election so from the get go not everyone can be a candidate, you need to have access to a certain amount of wealth.

There is also the fact that money has clearly a very important effect on the result since roughly 90% of the time the winner of an election is the candidate who spend the most on their campaign, this is the case for both the house and the senate.

There is also as you cited capital financing and legal bribes such as lobbying.

The results are also indirectly manipulated by changes on how the votes are counted, for example, if you pick the winner of the election district-by-district, the results may change depending on how you draw the frontiers of the districts, this practice is called gerrymandering. There can also be restrictions on who can vote (age restrictions or race or by removing your right to vote for life if you commit a fellony for example), the elections can be held a during a working day on purpose so that peoples who can’t take time of to go vote don’t have a say, etc…

A good video on the subject

Ha, and of course, there is no way the bourgeoisie is going to let us replace the current voting system with something that represent the peoples better so implementing ranked voting or any other voting system is but a pipe dream as long as they are in control anyway.