> Why would it not be possible to create a system that required several manual and offline steps in order to break the encryption?
When done correctly and with everyone's knowledge and consent, this is a form of key escrow. But there's some simple math at play here - the more unlock options there are, the more points of vulnerability and failure. https://haveibeenpwned.com/ lists 8 breaches of my data and I'm aware of more they don't list - the industry can't even keep my data under lock and key without adding more points of failure via key escrow as another thing they can fuck up.
> For example (and perhaps similar to offline cold storage of bitcoin) why couldn't a system be designed whereby 3 or more people in geographically diverse areas were in a position to agree that a request for information was legitimate (by court order) and thereby produce what is needed to unlock certain information? So one person would not have the key or access.
Bitcoin is a great example, in a way - there are several stories out there of exchanges fucking up and losing access to their coins or having their coins stolen, even when they were using cold storage. All 3 people will likely be duped by the same fradulent (or just overreaching) LEO email, in part because of the all too human tendency for each of them to assume that "one of the other two would have caught it if it was fishy, right?"
> After all right now you have a case where a single person (the owner) is able to unlock information. The feeling is a back door can be hacked. What if it's not a back door though?
The label you use doesn't matter - the more people who can unlock things, the more points of failure you have, and the more likely things will end up hacked. The industry struggles enough to secure things even when it takes a hard line approach and espouses end-to-end encryption. Defending against abuse by insiders/employees usually means going through a bunch of trouble to lock your own employees out of customer data - or making it unavailable to the company in the first place - not giving them more tools to access it.
Governments already have more than enough tools to completely pwn my privacy if they actually need to. Convince a judge to sign a sneak and peek warrant, have law enforcement covertly install a hardware keylogger, and I'd wager you'll pwn most people - even if they're tech savy. But that requires pesky things like indivudalized suspicion, "checks and balances", actual work, and involving multiple people (your landlord or a locksmith for the keys or entry access, your security company to silence the alarms, a judge to sign off on the warrant and a leo to execute it) so it's harder to run a long term secret warrantless suspicionless mass surveilance dragnet as a rogue employee or agency. But not impossible, as certain three letter agencies have shown.