The UK has a difficult relationship with identity, especially in recent years when providing identity to take part in society is becoming more important.
I have several relations who have had problems over the last decade or so.
For people who don't drive, don't travel abroad, don't pay bills (because they live in bills included accommodation or with relations), or maybe just get their bills delivered online, proving your identity is getting to be difficult.
My mother-in-law was wanting to rent a house while she was moving from one region of the country to another. Only had a paper driving license. Did not have a passport. Shredded bank account statements as soon as she had reconciled them. The letting agency wanted more documents than she could easily provide. It was very difficult to persuade them who she was, and it seemed like it was necessary because of a change in the law with regard to illegal immigrants.
My youngest son. Left school before he set up a bank account. Did not have a driving license or passport, did not pay any bills. Had no picture ID at all. Obviously did not have bank statements. We had significant difficulty setting up a bank account (eventually had to apply for a provisional driving license just for ID, and not everywhere accepts provisional licenses).
My wife. She's a beneficiary in a will. The solicitors what picture ID, but again, she does not drive, and does not have a passport. She doesn't work, so doesn't have payslips or receive any government benefits. She's also only on many of the bills as Mrs Gathercole. They won't even accept a person of importance (we know a local government Councillor) vouch for her. We're still arguing this one.
A non-compulsory ID card with biometrics, but without the large database backing it up (just enough to prove the card was issued by the government) would solve all of these. When applying for a bank account, credit, or any myriad of different accounts and services, it would negate the need for a huge list of 'identifying documents' that many organizations want.
What most people in the know objected to with the last ID card system in the UK was not the card itself, but the database and identity number that the Government was wanting to use to pull all of the government information about someone together as a super-index that could be added to existing databases relatively easily. The bill to introduce the whole system would have allowed secondary legislation (laws that don't have to be debated in parliament) to extend the database in any way that the Government saw fit, without any scrutiny (this is where it upset the House of Lords).
The other thing was that the government wanted people to pay for the privilege of having a government issued ID card, and to keep paying every 10 years or so, for something that they wanted everyone to have.
Since that time, the Government have realized that for all people of working age (and children, as they issue them while at school), the National Insurance number forms a perfectly good cross-data-source unique identifier, which is why they are asking for your NI number when interacting with vehicle and driver licensing, the NHS, and so may other things that really don't need the NI number.
Whilst it may seem obvious to people outside the UK that governments may want to marry say tax, benefits and criminal records together, we have a history of all of these things existing in disjoint databases that have been difficult to cross-match. We don't like the idea that the Government will obtain significant powers to monitor what we are doing, but at the same time, many of us are prepared to let the internet giants, banks, credit card companies, mobile phone operators, and any company issuing 'loyalty' cards or apps track us in minute detail.
Even though I am generally against ID cards, I would support a card that proves who you are without any anbiguity, although I would not want to make carrying it compulsory.