>Many corporations require personal devices be managed to support remote wiping.
Corporations cannot require you to have your personal devices be managed by them. If you're surrendering your own gear to a company, it stops being your own device.
But they can require things of devices connected to their wifi or being brought to their premises. You are welcome to leave the device at home if you don't want to consent.
Depends on the local laws. Where I live, they can either deal with it, or provide a secured storage space for the duration of the visit.
Either way, if a corporation wants their employees to use a device, they are obliged to make one available. Surrendering your private equipment to their management makes it not yours anymore.
Yeah you're 100% right that it's optional. It's usually only required to allow company data such as email, slack, file sharing etc on your personal device. If you're on-call it is VERY rare for an employee to win a fight on making the company provide a dedicated device for that purpose (which can inherently make it a condition of your job but that's an exception).
Most employees tend to not care about the why and are happy to just do it making "you" (the one bucking the trend) the oddball. The one not being the team player. It's not legally required, and you won't be fired for it, but its strongly socially encouraged and that makes it mandatory for anyone not willing to put up that fight.
On iOS there is the concept of "Managed Apps" that is appropriate for a BYOD scenario. They are info sandboxed and can't share information (either direction) with unmanaged apps. That would count as an MDM enrollment, if you are looking for it.
Corporations cannot require you to have your personal devices be managed by them. If you're surrendering your own gear to a company, it stops being your own device.