the total spending on US *congressional* races in 2024 (not including the presidential race) was $9.4 billion. the equivalent figure for the last UK general election was, conveniently enough, 94 *million* pounds ($126 million.) Campaign finance laws work!
One thing I've noticed, doing global reporting, is that American electeds are considerably more organized than their peers elsewhere. Offices are bigger and more professionalized, campaign techniques are more advanced and data informed.
Differences are striking, though I'm not sure why they exist.