"I don't know why so many are against the reintroduction of ID cards, no one seems bothered regarding Birth Certificates, Marriage Certificates, Driving Licences and Employment ID Passes."
Simple. As a citizen I should not have to carry or even provide papers to prove myself valid to the State. The State should be proving itself worthy to me. If the State has valid doubts about me let it prove them.
Certificates to indicate one is born, married, capable of driving, or employed are clearly not so totally obnoxious. It doesn't relate to me having to prove myself as an individual citizen or else being considered persona non grata. We all deserve more respect than that.
The State exists to benefit the individual citizen, the individual citizen is not there to be pushed around by the State. The priority is the wrong order when papers are demanded.