I was only half joking previously. Why require a solution when you can remove the problem instead?
IP addresses work fine, like phone nmbers and street addresses.
Non-technical people will likely not recognize four three-digit numbers separated by periods as being an address for a website.
And phone numbers have been largely supplanted by contact lists on phones (I've occasionally forgotten my own number). Looking over my call history, out of the last fifty outgoing calls, six are not in my phone book and all but one of these were dialed directly from search results on the phone.
I highly doubt showing the domain prevents any meaningful amount of phishing attempts.
Please, do elaborate on what other ways of phishing preventions you have in minds.