"We have never built." ok, so then who built it?
The feature is not named "back door" or "master key". It's a feature of iMessage with various names such as "zero click".
Also note they have created features before that provides law enforcement access to data at different stages of a pipeline.
All web results for `imessage "zero click"` are about vulnerabilities/exploits. Are you claiming some of these are intentional, or what?
"An Israeli spyware company has reportedly cut access to its clients in Italy following allegations that its product was used to target critics of the Italian government.
"The move comes after WhatsApp alleged last week that spyware made by Paragon Solutions was used to target 90 WhatsApp users in two dozen countries, including journalists and civil society members.
"Italy's government confirmed in a statement on Wednesday that seven mobile phone users in the country had been targeted by spyware on WhatsApp, calling the incident "particularly serious"."
(Not that the article has any evidence supporting the same claim about WhatsApp, either. In fact, the article describes WhatsApp/Meta claiming to have "disrupted" the spying and reporting it to the Italian government.)
The communist party doesn't have "access" to a billion phones: what would they even do with all that garbage. They can ask Wechat what you send your friends, sure, and that's enough to police most crimes.
We don't have the budget or organizational acumen of the NSA.
Apple (and many other organizations) contracts work out for liability reasons, this is not the first instance of it.
Also note the language - specifically a “back door” or “master key”. If you call it something else, literally anything else, the statement holds up.