Are they really astronomical levels though? Compared to other countries? The UK puts in just over $3k per year per person. If you combine government funding and compulsory health insurance (which is effectively another tax, since it's compulsory) in other countries, you'll find that most of Western Europe is paying more than that. In France and Japan (2014), it's approaching $3.5k, and Belgium and Ireland are both around that too. Austria is in the high $3,000s. In Sweden, Germany, Denmark and the Netherlands, it's over $4k. The only difference is that a lot of these countries have an insurance company in the middle making profits, and none of them see significantly better results than the UK and all of them come below the UK in terms of efficiency of their health services. In terms of GDP percentage, the UK also doesn't spend as much as lots of other countries. We spend 9.7% of GDP on healthcare, compared to Austria, Denmark and Belgium (all 10.4%), Norway and the Netherlands (10.5%), Canada (10.6%), Japan (10.9%), France and Sweden (11%), Germany (11.4%) and Switzerland (12.4%). It's worth mention that the USA spends 17.2% of their GDP on healthcare, so government funding isn't everything, especially if it's being used to subsidize the profits of huge corporations.
In the Netherlands, you have to pay around €100 a month out of your salary for health insurance, but as you might imagine, poorer people get that subsidized. On top of that, you have to pay the first €385 per year of healthcare costs. The government just sets and enforces the rules, but everything else is privately run. And people who say that private companies run everything better would presumably argue that they do better, but is this the case? What do they get for their extra 33% funding? Is it 33% better services, or just a nice profit for the insurance companies? Every comparison I've ever read seems to put the UK as better in some areas and worse in others, but crucially, always better at the efficiency we're always told that only private businesses can offer (just like they have on the trains).
Here's an unbiased comparison. It's quite amazing how well the NHS does when it's probably dealing with the most unhealthy population in Western Europe.