At first glance we would criticize the catechism for not addressing covetousness here. Why do we find the approach of speaking of ALL the commandments and making it a matter of the heart?! The 10th commandment brings us to the depth of keeping the law of God however and we with them cannot keep them bring us completely back to Christ in whom we can keep them in principal not only, but also spurs us on to lead a new and holy life!
Idea: Covetousness is approached from a negative aspect. It is to yearn for or pine for something. One can covet positively (...covet the best gifts...) but the law speaks to that which I desire after. That which the Lord has not given to me and has given to the neighbor. We may not covet in either the first or second table of the law! To covet always has to do with the heart. It is NOT the action but rather the MOTIVATION and the heart! He judges what is within. We must in our whole being love God and hate sin! The catechism addresses the struggle of the old and new man in our flesh. The catechism does not ask us "do you keep the commandments....but note that it asks here "CAN you?" We must ask in the negative as even the holiest of saints cannot keep them. Just read and study the heros of faith in scripture to see proof of this very fact.
Reality: Even those with the new life in Christ Jesus have ONLY a beginning of that new obedience. As the children of God we are forgiven! God looks at us as we are in Christ Jesus even though when we look at ourselves we see ourselves as grievous sinners in the mirror. We now have an aptitude to good works that come from the heart whereby God works. The workmanship of God and they are unto His glory! "Praise in the common words I speak, life's common looks and tones..." as the song goes. Do we realize that EVERY opportunity in life affords us the OPPORTUNITY to praise and glorify God?!!
Fruit: In order that we may walk therein. Don't bypass the opportunity and relationship. Take hold of it to His glory. We often think things stop with us...but this is NOT the case or father from the truth! It is ALL to God's glory...both now and into all of eternity!