"Keep in mind that wasn't an accidental difference. In Germany, the publishers that opted out of the scheme (and kept their presence in Google News) benefited from absence of those who didn't opt out, which created a motive for all publishers to opt out in a sort of tragedy of the commons situation. The Spanish lawmakers wanted to prevent that."
The legislation is an attempt to create a law mandated news cartel:
"In economics, a cartel is an agreement between competing firms to control prices or exclude entry of a new competitor in a market. It is a formal organization of sellers or buyers that agree to fix selling prices, purchase prices, or reduce production using a variety of tactics." (Wikipedia).
If they had been succesful the consequence would be that Spanish media consumers would have to pay more for their news. Fortunately it seems like they will not be succesful and hopefully Spanish consumers can use foreign media outlets that are not part of the cartel.