Political maneuvering can involve such minute actions as to seem arbitrary. Consider this account from state Representative Rod Driver (D, Charlestown, Exeter, Richmond):

During consideration of the state budget, on June 24, I offered an amendment (requested by several towns) to relax the mandate that public-works projects must be performed by contractors who pay “prevailing wages,” i.e., union scales. (Try explaining to a person living on Social Security that she must pay higher real-estate taxes so that painters or roofers — perhaps from out of town — working on a town building can be paid $44 an hour, including benefits. Meanwhile, willing workers in town remain unemployed.)
My amendment would have removed the prevailing-wage mandate only for small projects, under $50,000, and only for the fiscal year July 2009 through June 2010.
But House Finance Committee Chairman Steven Costantino suggested that it was “not germane.” House Speaker William Murphy consulted the parliamentarian, and then announced that my amendment was indeed “not germane.”

Subsequently, Rep. John Loughlin (R, Little Compton, Portsmouth, Tiverton) offered an amendment to withdraw all mandates on school committees except those related to safety. The House leadership permitted that amendment to be voted down.
It’s possible the reason was mere arbitrary whim, but it could be that opposing Loughlin’s amendment could be spun as protecting kids, while opposing Driver’s is much more directly a sop to a special interest. Even for the handful of people who actually pay attention to this stuff, parliamentary procedures are abstract and allow a bit more slither room if anybody takes notice.