To be fair, that is from a linked set of questions, and the URL says "british-or-irish/no". I'm fairly certain it's the list of things you need to show if you don't have a British or Irish passport
It's the opposite - it's if you're a British/Irish citizen and don't have a passport.
Many countries use Digital ID cards which update immediately. Only your ID and perhaps your health/driving entitlements really need to be on there. No need for bus passes and railcards to be involved.
How it works in Poland: the ID card contains really the essentials, whereas everything else is stored digitally. It's not quite perfect, but for instance, my driving licence is completely out of date in terms of address. It doesn't matter: the card is really only there for driving abroad. If I get stopped by the police here, they know everything (including my photo) from my Polish national insurance number, so there's no need to show them ID or a driving licence. Things like being given a "producer" is unheard of here: it's all digitally stored and the police can find out everything they need to know from their in-car computers.
From 1961 to 1995 you could get a British Visitor’s Passport, which was valid for one year, with which you could travel to most of Western Europe except by land to West Berlin
By the end, you could (at least until 1991-2, not sure what happened with the post-1992 states) go to Yugoslavia too, as well as Tunisia and Canada. It's quite incredible to think you could reach Greece overland with it. The actual idea was based around the loosening of post-WW2 travel restrictions, where passports/visas were no longer needed for travel within the EEC, just ID cards. As the UK didn't have ID cards, the BVP acted as a de facto ID card for travel.
Generally it is, but for some reason a passport isn't an accepted form of ID in the link posted by @Cloud Strife
The problem is if you don't have a passport, which I find to be really insane. An ID card solves all this instantly by having a single universal document, but instead the UK goes to ridiculous extremes. In comparison, if I want to sign a contract with someone, like a rental contract, I simply ask to see their ID and write down the number of the document. Job done. In fact, as our ID cards are also on our phones, we can even verify whether what they're presenting is valid through simply scanning a QR code linked to the (digital) ID card that they've presented.
From an economic point of view, just how much time and money is wasted with all this bureaucracy?