Simply spending money to get someone you like elected isn’t bribery.
To the degree great inequality leads to this being decisive in elections, it is a corrupting influence, but the term for it is still not “bribery”.
But when a presidential candidate tells oil companies they should donate because he is going to help them, that’s solid bribery.
When companies pay to “settle” ridiculous accusations, or “donate” to a president’s causes, while their mergers or other business legal issues depend on an openly pay-for-play president’s goodwill, that’s solid bribery.
The country’s policies, discipline, reputation and competence (economic, diplomatic and political) are being sold off for a tiny fraction of what their future adjusted value is worth.
In actual functioning democracies political donations are capped severely.
Say, a single donor can contribute a maximum of €6,000 per parliament candidate per election.
Yes, that's a real limit.