The publishers in question found that their images and headlines were simply removed from its service, prompting them to accuse Google of blackmail.
It's a little bit hard to make the case that Google should be forced to display their snippets and pay for the privilege. Seems to me, giving the permission to Google should be considered as a cost of doing business, just like marketing. If your competitors pay more for advertising than you do, your sales will suffer from it. And if your competitors allow Google to display their snippets and you don't, your traffic will decrease.
Google News is a place where publishers have to compete for attention. They can refuse to participate, or dictate what Google is allowed to display of their own data, but they can hardly complain that other publishers are willing to go further than them; no more than they can complain about their competitor's bigger marketing budget.
Of course, big publishers might well consider that it's more advantageous for them to just make Google shut down the whole service like in Spain. Users probably then search for news on the biggest websites, to the detriment of smaller ones.