One one hand, lobbying means interfacing with government leaders directly; engaging in face to face communication, and building relationships so that your interests are heard. No one thinks that's bad.
However, the US has taken many steps since well before Citizens United to build a kind of legal fiction which has made bribes legal, which is wrapped in the same language as what I'll call "ethical lobbying." As the OP points out, as long as on the record there are enough levels of separation between the politician and the person or organization giving the money, it's completely fine. The fact that the CEO and the politician are having lunch together is just a coincidence as they are definitely old buddies who have a shared mutual friend.
This problem has existed for a while in the US, but the Citizens United decision and the expense of running re-election campaigns has made it far, far worse.