They are a mandated barcode which will link every aspect of your life and provide the Government with complete oversight.
A single file will contain your financial information, health records, tax records. The Government will keep a record of every job you apply for, not just the job you are currently doing, but every application you have ever made. It will be worse than any dystopian movie ever made. 1984 will just be the starting point.
Imagine a world where every interaction is tracked and logged by the state. It can't stop illegal immigration or tackle illegal working, that was never it's purpose. Which is why no Labour politician will answer questions about it.
Other countries have National I.d cards, but Digital ones can be abused, this is an important distinction. A physical card is used as I.D, a digital one is just a barcode to collect your data. For example, currently you might have to show your I.D to buy alcohol, this isn't logged anywhere. But once introduced, Digital I.D will be used instead, so now the Government knows when and where you tried to buy alcohol. They will make it mandatory that when booking flights, alongside your passport number, you must put your I.D number. Now they have a means of cross checking when you fly. It will be the same with train tickets, EV charging, you name it, you'll have to scan your I.D to access it.
That's the problem. The mission creep that will occur. Your I.D will be used to control and monitor you, a digital leash. When "the computer says no" you will not be allowed to travel, apply for jobs, use your bank account, even driving will be monitored as all EVs will require you to scan your I.D before the car will let you drive.
Ultimate state control over your entire life.
The ways in which a digital I.D can be used to control you are limitless. If you have to scan your I.D, you can be controlled at the literal press of a button.
They must be resisted and stopped.