Why would it be cheap if it is effective? It’s a zero sum game and there are intensely competing corporate interests. If it were highly effective, the price would be bid up.
Because there are way more politicians than there are companies?
How does Google and company use their lobbying budget to bribe a politician? Vacation to the Maldives?
Funding their campaign for re-election in the form of ads.
In what way does Google provide advertising favors for political campaigns? Discounts to their ad program? Downgrading opponent visibility?
Google can’t fund anyone’s campaign for re-election.