It's exception, not rule. Even if they want you to give name, it's not something available for others if they only have e-mail address (unless address contains name).

In the UK I don't think it's possible to get a credit/debit card without giving up name & address that are backed by ID.

Gmail, IIRC, requires a phone number, which again is tied to your payment account (if you buy it in the UK). Though you could buy a stolen pre-paid SIM, so it's possible if you're not bothered about being legal.

In USA I understand you have pre-pay credit cards you can buy in a shop, in the UK you have to register those (using a phone number IIRC, thus tying it to a supposed real identity) and they're really expensive.

Even with custom domain, there are some mail providers that accept Bitcoin. See here: https://www.privacytools.io/providers/email/

And, once more: my previous point was that even if providers know your id, it is not public. There is no service you can use to ask what is name of e-mail address owner (I'm ignoring "whois", which is domain-specific, not mail).