And how do they thwart them? Simple: they have the Cellbrite cracking device.Apple continually introduces improvements to the security of its operating systems in order to keep ahead of companies like Cellebrite that are always searching for flaws and vulnerabilities to exploit in order to access the data on locked iOS devices.
What I heard from industrial chatter is that Apple posed as security firm working for law enforcement (they even set up fake shell company just for this purpose) to obtain the devices. After figuring out how it cracks the OS, Apple patches it up in subsequent updates.
As long as Apple can keep up (they have multiple fake shell company posing as security firm) this will keep iOS very difficult if not impossible to crack without some chip flaws in Apple Silicon.