While I can understand your point about collaboration for the good of the Universal Church, and that this is, in fact, something that is one of the duties of the Bishops, I must object to your characterization of our Bishops as “little king(s)”, and their Dioceses as “little fiefdom(s)”.
I would rather characterize our Bishops as our shepherds, and successors to the Apostles.
See Lumen Gentium 20:
Therefore, the Sacred Council teaches that bishops by divine institution have succeeded to the place of the apostles, as shepherds of the Church, and he who hears them, hears Christ, and he who rejects them, rejects Christ and Him who sent Christ.
But the faithful must cling to their bishop, as the Church does to Christ, and Jesus Christ to the Father, so that all may be of one mind through unity,and abound to the glory of God.
See Lumen Gentium paragraphs 18-27 for further reading (including a discussion of your point on collegiality).
Again, my objection does not go to the the merits of your argument about whether or not the Bishops are able to agree with one another, nor to the practical, prudential, or financial considerations of publishing catechisms. I just wanted to lodge my objection to your characterization of my Bishop, to whom I owe my obedience and docile reverence.
We now return you to your regularly scheduled program