This kind of behavior is needed for: - Public transit and digital IDs. It sucks when phone dies and you can’t get out of a station or show your driver’s license. - Power management. Power buttons on modern phones are digitally controlled by a microcontroller because actually switching main power by those buttons can glitch the phone. - Firmware updates. Phone has to be able to handle USB connection to accept new firm…
There's nothing that requires a microcontroller to be active during power-down to handle the issues you describe: For transit passes and IDs, there need to be non-phone-based ways of handling that issue. It's equally possible to lose / have your phone stolen. Talk to the station agent, or have the police look up your license by name / address. There's no need for a continuously-running microcontroller to read the pow…
It’s interesting, here in the U.K. you have a legal obligation to present a valid ticket upon demand for any train you travel on. Failure to do so for any reason (including my phone died, or I dropped the ticket) is a criminal offence (and I mean criminal, not civil) punishable by a prison sentence.
Some ticket conductors at the end of a long shift hearing endless excuses about why someone doesn’t have a valid ticket really aren’t interested in negotiating. They’re quite happy to enforce the law, and make your life a living hell in the process.
Personally I much prefer it if the transit pass on my phone keeps working after it dies. The alternative is very… inconvenient.