A Scout is reverent. He is humble. He is respectful. He walks with quiet dignity.
Reverence is an internal expression although there are outward signs but unlike the Publicans, a Scout is not reverent to obtain awards or glory but as his duty to God.
2 Therefore when thou doest thine alms, do not sound a trumpet before thee, as the hypocrites do in the synagogues and in the streets, that they may have glory of men. Verily I say unto you, They have their reward.
5 ¶And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward. 
The LDS Church utilizes Scouting as the activity arm of the Aaronic Priesthood. LDS Scouts obtain the Aaronic Priesthood and through exercising their duty to God learn reverence and respect for that which is spiritual and is used to bless others. Scouts learn this kind of reverence in their youth as they prepare to take on the higher priesthood of God, that of Melchizedek.
…The greatest manifestation of spirituality is reverence; indeed, reverence is spirituality. Reverence is profound respect mingled with love. It is “a complex emotion made up of mingled feelings of the soul.” [One writer] says it is “the highest of human feelings.” I have said elsewhere that if reverence is the highest, then irreverence is the lowest state in which a man can live in the world. …
Reverence embraces regard, deference, honor, and esteem. Without some degree of it, therefore, there would be no courtesy, no gentility, no consideration of others’ feelings, or of others’ rights. Reverence is the fundamental virtue in religion. It is “one of the signs of strength; irreverence, one of the surest indications of weakness. No man will rise high,” says one man, “who jeers at sacred things. The fine loyalties of life,” he continues, “must be reverenced or they will be foresworn [or rejected] in the day of trial.”
I look upon reverence as one of the highest qualities of the soul. An irreverent man is not a believing man. …
I am prompted to place reverence next to love. Jesus mentioned it first in the Lord’s prayer: “Our Father which art in heaven, hallowed be thy name. …” [Matthew 6:9.] Hallow—to make holy—to hold in reverence. 
On the twelfth day of Christmas a Scout walks in reverence and respect, a manifestation of all the attributes in the Scout Law. Hence the reason that reverence is last in the law.
Author: Heidi Sanders | Marketing & PR Director, Utah National Parks Council
1. See Matthew 6:2-5.
2. See Teachings David O. McKay, “Chap. 4: Elements of Worship.” LDS.org.