Also, let's not forget the FBI had a back door entrance.
They used it for quite some time.
The phone was actively syncing with iCloud, they could have installed any number of existing applications that let them get control that way. But they chose not to use one of the existing attacks.
For reasons they never really explained, the FBI investigators changed passwords on the account and broke the sync.
Now they're demanding Apple help them build this tool that helps them brute force the password. Everyone is watching.
The key is that this is software and hardware, hundreds of millions of machines that are all identical and susceptible to the same software tools.
New York has already stated that if the FBI can force the precedent, they've got nearly 200 phones they want the treatment for, which courts have so far denied because it isn't something that exists. Certainly many other police agencies around the US would also jump in that line. Then there are all the other governments around the globe, they're going to have their own court battles, and so far they've all seemingly gone along with Apple's line that there is nothing to be done. If this tool gets created, there are all of those too.
That is part of why this is such an important case.
If it were a case of handing over something that existed, with a specific warrant or subpoena for the specific thing to be surrendered, that would be different and apple should comply.
This is a case of building a tool that works on hundreds of millions of devices, a tool that does not exist, and the government (through the FBI) are trying to force them to build it against their wishes. That is a radically different issue, and one I believe this initial court got very wrong.