"My first assumption is that they don't have deep enough pockets to go up against Google"
The entire entertainment industry is only worth some $100 billion.
When the studios started going after Youtube I speculated that Google could simply purchase them with change from down the back of the sofa
However we should bear in mind that Sony purchased BMG and several movie studios to head off lawsuits relating to their hardware - and swallowed a poison pill in the process
As people have been pointing out for 30 years, the heyday of music profits was the late 1960s/early 1970s. When CDs hit the market, album sales were already down ~50% on 1970 and single sales about 90%. Media refreshing sustained the industry for a long time but by 1990 it was in terminal decline again - which is why "piracy" became the BBEG target
The movie industry went through something similar
In reality both of them are like the sheet music industry going after player pianos (which happened)
The biggest abuses of copyright (and most lucrative acts of outright piracy) are performed by major companies - I think they went after hobby sites because they couldn't stand the competition (Note that Mega became a target only after it announced music deals signed directly with artists and the process turned a pretty awful human being into a folk hero)