The cost principles shape what gets funded by stacking filters. Each one - necessary-and-reasonable, allocability, prohibition analysis, supplement-not-supplant, approved-plan alignment - is its own clearance gate. By the time a cost has passed all of those, the path of least resistance is to fund what's already cleared the gauntlet before (ie. Repeat vendors, recurring contracts, standard equipment kits, the same conferences). That bias toward the already-cleared is the single biggest practical effect. It shows up as programs slowly narrow into a smaller and smaller set of activities.
In my opinion, it also tilts spending toward the utilitarian and away from anything that builds program culture. Student recognition events, certification completion celebrations, teacher appreciation tied to retention -- the federal standard doesn't prohibit this, but the entertainment-cost gray zone creates enough friction that most admin default to not trying. Programs meet the technical requirements and risk losing the very human-centered glue that keeps students and teachers in them.
Allocability does something similar with equipment. A 3D printer used 60% for CTE and 40% for general engineering can't be 100% Perkins-funded. The defensible move is to buy two -- one CTE-only, and one general - which is more expensive overall but cleaner on paper. So the principle quietly biases toward duplicated equipment in well-resourced districts and no equipment at all in under-resourced ones.
The piece that matters most to me, though, is that the principles cut both directions but only one direction actually gets enforced. The restrictive cut -- don't spend on the wrong thing! -- is policed by fiscal officers, audits, and conservative interpretation. The compelling cut -- do spend on the right thing, because failing to do so also fails necessary-and-reasonable -- is not actually policed at all. A vendor we don't need stays in the budget for years. A vendor we do need stays out of the system for years. Both fail the same standard. Only one gets corrected.
The ugly and unfortunate side that I have experienced is a net effect of programs doing what's defensible rather than what's strategic. The principles were designed to prevent waste. One of their unintended effects is to suppress what the law actually allows.
