Getting immunity will eventually make them as bad as the carriers once they form "relationships" with the government, or when they want to win some big fat government contracts.
Microsoft already "needs" to win multiple contracts with the government, and Apple is supposed to "win" Apple Pay integration with federal services.
If all the data requests would be legal then they shouldn't need immunity, should they? This is 90% of the way the encryption backdoor the government has been requesting. That's why it's "backing down" on that.
Much like what Microsoft has already been doing years before this [1], the NSA will get Apple, Microsoft, Adobe, Oracle and others' zero-days ~3-12 months before they are patched, as part of the "cyber-threat sharing" program. That's as good as having dozens of backdoors in tech companies' software that billions of people are using.
Michael Hayden, who formerly directed the National Security Agency and the CIA, described the attention paid to important company partners: “If I were the director and had a relationship with a company who was doing things that were not just directed by law but were also valuable to the defense of the Republic, I would go out of my way to thank them and give them a sense as to why this is necessary and useful.”
This is how they are thanking them, by giving them immunity.
[1] http://www.bloomberg.com/news/articles/2013-06-14/u-s-agenci...