It doesn't, money has surprisingly little effect on competitive elections
If media presence had surprisingly little effect on outcomes, then I would expect candidates to spend surprisingly little or be constantly outperformed by "underfunded" candidates-- neither of which is the case.
It's the same thing in elections. Because everyone is competitive, who donates what money or it's amount tends to not really matter. If a candidate were to sabotage their campaign they would lose, but in a competitive election it doesn't end up being statistically significant.
Not sure how you're defining "underfunded" candidates, but the incumbents in competitive races where enormous amounts are spent by both sides to try to gain an advantage don't win anywhere near as often as the incumbent in nom-competitive races which parties and PACs barely bother spending in. Ultimately the spending is positional and cancels out, and the biggest spender often loses because there's not nearly enough difference between the candidates' spending levels to affect whether voters hear their messages.
There is a lot of money in America, and comparatively not that much is actually spent on the election. Maybe it's still too much in an ostensibly democratic system, but it's worth noting.
It's not really helpful that the number is tolerable in terms of national GDP: election spending being so large in terms of median wealth simply excludes lots of capable potential candidates that are not well positioned to raise money (for whatever reason).
It also leads to completely outsized pandering to "rich donor" interests, because those finance the largest share of the campaigns, which is an obvious problem if you want to call yourself "democracy" (instead of oligarchy or plutocracy).
Which laws and which books? I can't find anything.
While (as far as I know) the law was never actually used to ban books (only documentaries), the case became infamous because the government argued that it had the right to ban books if it wanted to. See, e.g., the NYTimes article below: "The [government's] lawyer, Malcolm L. Stewart, said Congress has the power to ban political books, signs and Internet videos, if they are paid for by corporations and distributed not long before an election.".
https://www.nytimes.com/2009/03/25/washington/25scotus.html https://en.wikipedia.org/wiki/Citizens_United_v._FEC https://www.law.cornell.edu/supct/cert/08-205
money is not the only factor.
may not be the most money, but it's the most effective use of money.
PA roads were littered with trump signs because of people being paid to litter our streets with them. for months.
people are, sadly, very easily influenced. companies wouldn't pour so much into advertising, in general, if it didn't have such an effective influence
[0] https://www.usnews.com/opinion/articles/2024-11-15/trump-har...
Most campaigns stretch the truth a bit here and there, but from what I personally saw and from what I read from other states where the campaigning was more intense generally the Harris campaign did not stretch nearly as far as the Trump campaign.
I'd expect that this let the Tump campaign get more out of a given amount of spending than the Harris campaign could.
Furthermore, in a country with somewhat free media you would always expect populist candidates to outperform with a given budget, because their platform is much better aligned with media interest; mass media does not want boring budget plans or quaint reforms-- rage-bait sells way better and nets populists tons of "free" online presence.
"Absolutely, money does have a measurable impact on political outcomes"
https://www.investopedia.com/surprising-thing-billionaires-s...
https://www.opensecrets.org/elections-overview/winning-vs-sp...