How come no one is mentioning the obvious solution -- LaLiga needs to make their product as easy to access as piracy. If they offered worldwide streaming of the matches available on an easy interface at a reasonable price, then none of this would be a problem.
Piracy is almost never about the price -- it's almost always about the availability. Especially when it comes to live sports.
I suspect it's not quite that easy: it's likely similar to the situation with the Premier League in the UK (and other things like Formula 1 previously) where a particular broadcaster has been given exclusive distribution rights, and has paid a lot of money for those rights (which in theory go back into the game and pay for the huge salaries of players).
This solution clearly does not actually work. Musicians make pittances off of streaming in comparison to the money they made with physical media. Hollywood has seen strikes and streaming services continually raise prices.
Musicians make very little off physical media - it's merchandise that brings the money in.
With piracy they make nothing, so they'd still make more than they make today. Almost all of the pirates are people trying to watch from outside the coverage area. It's not like stopping piracy gets those people to pay.
They just stop watching.