I'm not sure it's Democracy that's failed. Systems are dumb and mute and are only as effective as the men who martial them. The only thing a system dictates is whether or not it has inherently built in (agreed upon) an absolute freedom that it itself affords the ability for men to destroy it with it's own precepts.
We've allowed it and like you'd stated, money has become the driving force instead of the will of the people. It's not even hidden that they're prostituting themselves out to the highest bidders and frankly the common mann can't match that.
First, I reject the idea that things would be any better if government did not offer government perks for campaign donations. Stalin by all accounts was completely free of corruption. No one could buy him off for anything... and last I checked he slaughtered more people any anyone in history.
Second, it's fairly nutty to ever assume that a politician would not offer government perks for money. Why would you ever conceive that there are some benevolent Angels in the world that you can elect, that will never be corrupted by the power they wield.
You give them tons of authority, and then give them tons of potential lobbying issues, and then think they shouldn't act on the situation that YOU put them in?
Kind of like giving your 5 year-old child 500 boxes of chocolate candies, and then telling him to keep them in his bed room, and then saying... "oh but don't eat them".
Human nature hasn't changed in at least 6,000 years. But you think if you can just find the perfect person in congress, they'll be divinely perfect in their conduct.
Get over it.
The only thing you can do, is remove from congress the power to abuse. By removing the ability to tax with insane taxes, no corporation will find it worth money to lobby for exemptions. Ta-da! No demand for exemptions, no lobbying for special exemptions, no donations for tax breaks. System fixed.
But instead you think we just need more taxes, more regulations, which just gives the politicians more power to take donations for exemptions, while you complain about them "prostituting themselves out to the highest bidders". Hello.... look in the mirror. That's the guy who is causing this.