A register with little or no meaning - a sham

It is now practice in some Catholic churches, not all, that a priest signs a register before celebrating Mass.

Many churches have such a book, others don't. In some churches where there is a book the signing of it is done in a haphazard way.

What exactly is the purpose of the book or register? Is it a real attempt to put in place some sort of professional behaviour in churches in the State?

Or is it some sort of legal reaction, some sort of attempt at PR to make the church look better?

Whatever its purpose it does not work.