I'm in favour of ID cards, it's a good idea. Across the world most countries have some form of ID card, both in Europe and worldwide. Some are compulsory, some are choice to sign up. Only 10 countries have nothing like this at all, including the UK.
When I was in Norway, I was really impressed with their system. Their national ID number is a requirement for all citizens and anyone living there for any length of time. You can't stay long term without obtaining the special number first. Without it, you can't remain in the country, you can't take on a job, you can't rent or buy a home, nor get medical care, nor open bank account. Certain things can't be bought without the number and you can't vote....it covers everything. It's impossible to "go under the radar" for long. Yes, it does store everyone's data but even that's helpful.....they don't go for long complicated (and expensive to run) census every 10 years because they can track everyone and the information they need all the time. Brilliant!