If you introduce ID cards, it soon becomes illegal not to carry one, is this really the way we want to go? Every time it it scanned it would reveal where you are.
But in future generations babies will be microchipped at birth, and that chip will store all their medical records, personal data including religion, sexual preferences, banking data, criminal offences, and tracking facilities. Great for parents when their child has wandered off, but terrifying if you are trying to avoid a stalker or abusive partner. The management of the massive database behind it would be wide open to hacking as millions of people would have access to it, NHS, police, local government, DVLA etc. For access to any service, to shop, to get treatment, you will just walk through a scanner.
Today some of us worry about privacy, but it doesn't bother a younger generation as much. By the time their children and children's children are growing up, every move will be tracked, and no-one will think anything of it. But thankfully I won't be around! 