I have been using Apple products a long time. Long enough that my Apple ID didn't actually start that way, and was originally a MobileMe account. I did, however, have an issue with one Apple ID where the required second email address was inaccessible and an entire account and all data with it simply had to be abandoned. Apple support informed me that there was zero recourse.
These days, I have multiple email accounts and devices, and recovery would be very simple. However, this is not true for all people who require an Apple ID.
My employer defaults to using Apple devices, and we use enough of them that we have an Apple Enterprise Support account and purchasing pathway. This is a decent set of services with the exception of never being able to use email for anything. No asynchronous communication paths are allowed. Instead, interactions take place via phone. You can buy stuff without a phone call, but that's it. That is true everywhere but on-boarding where you talk to your sales rep via email. So far, all communications I've had with Apple are complete garbage. No one seems to read a damn thing, and they don't really listen too well on the phone either. Additionally, the communications with support are never consistent. Sometimes one rep requires a certain amount of information or certain methods of doing things while a different rep doesn't have the same requirements. Via email, you can repeat multiple times that you have issues with something and no one cares. Apple can never admit any error may have occurred.
The single most annoying piece of this puzzle is very similar to alternate email address requirement that Apple has. That's right, Apple doesn't like to use email for anything, but they sure as heck make you have at least two addresses. In this case, creating a new Apple Enterprise account does not require you to have a phone number, device, or alternate email address. As such, you are lead to believe that security questions as well as your username and password would be enough to enable login, but this is not so. Upon attempt to login to anything (including support) you must have a phone number or a registered device to which a security code will be sent, and without them you cannot login. You cannot login to support to get support for logging in. All requests for help or assistance will either be ignored or you will be asked to login to Apple Support... yet, you can't login to Apple anything which is the entire point of the request. This isn't a small account or anything either which is even more damning. Apple simply fucked up this process. Effectively, you must give Apple every single field in their sign up forms, and you must never lose these alternate avenues. If you do, your account is gone, and Apple Support cannot help you over email, so you will simply lose the account entirely regardless of any money you've spent.