People keep repeating this as if PRISM was a voluntary, or even secretly cooperative, program.
PRISM was no such thing. PRISM was the US govt snarfing up whatever data they could (under questionable legal authority), but no one has ever alleged that the data they were snarfing was provided willingly or knowingly by Google, Apple, etc.
These companies are also victims of PRISM, not participants.
All have explicitly refuted claims of any backdoor into their systems. There is no evidence that they are lying, or being forced to lie.