The problem is that the internet made the "news" market way to efficient. Competition is incredibly fierce because the cost of distribution has plummeted, and because it turns out that most people don't read news for news, they read it for entertainment. If Google were to go away tomorrow, the publishers would be in the exact same position with Bing, DDG, Baidu, or whoever picks up the pieces. The economics have shifted, 90% of publishers are now offering a very low value product.
If governments go out and create this artificial market to prop up the "news" they like, not only will it be prone to corruption (What counts as an eligible publisher? Does Google owe the Daily Sun and the BBC the same amount of money? If it's different, who decides by how much?), but in 30-50 years, we'll be talking about the news subsidies the same way we talk about farm subsidies today; a corrupt and wasteful relic from an era that refused to acknowledge things have changed.
All that being said, the sales tax on digital adds is probably the best idea so far, but enforcement is going to be tricky.