Anyone who believes you can get "money out of politics" is naive or stupid -- or both. Money / power / politics are essentially different parts of the same whole. They go together and are inextricably linked. As such, the notion that we "need to get money out of politics" is completely asinine, it's not only not possible, it's not desirable to try.
Yeah, it's not like owing 20 trillion dollars is in any way going to affect our country, who cares right? It's only future generations that are at stake.
Finally, some sense.
First, how do you know the influence of the money is lessened? The fact that less is spent doesn't prove the influence is lessened, it just means less spending is needed to buy the desired level of influence.
The amount of money spent on elections is always going to be proportionate to the amount of power/influence wielded by the government, regardless of laws or restrictions. I don't know enough about the UK and it's political system to understand the factors driving spending on politics and elections there, but what exactly is it about the UK system that you think is the cause for the comparatively smaller spending? How would it compare to the US?
The brits are a lot more comfortable doing away with individual rights in the name of some supposed common good (stuff like criminalizing speech that might offend someone is a good example), so they might be much more inclined to stifle free speech and restrict monetary donations than people in the US would (or should) be comfortable with.