Lobbying is fine. The problem with the US is you can literally buy votes in the legislature. That's because the legislator's individual votes were made public via sunshine laws. As long as you keep those votes visible they can be bought no matter how much indirection has to be introduced.

The alternative is a secret vote. Now only passed/unpassed legislation can be bought. This is a lot more expensive and requires a conspiracy, but it's a lot harder to hold the people in this conspiracy directly accountable since they can always plausibly deny how their vote was cast. I've yet to see another better solution for getting rid of the money to vote pipeline.