Is a physical census head count accurate? Can technology better facilitate a census count?

Question

The purspose of a census is to aportion political leadership. It is posible to capture a near accurate count with access to birth records, death certification, immigration documentation, renunciation of citizenship, and deportation database information.

Answer 1

It sounds much better than a physical count but will never be accurate when we have so many illegals.

Answer 2

That will only ever be 90% acurate at the most. People are not all honest. Some are, others are not.