Freshness, consistency and control — the practical reasons small batch blending tastes different.
Spices are perishable. Volatile oils carry most of what you taste, and they start leaving the moment a spice is ground. Small batches shorten the distance between blending and cooking.
Small batches also allow correction. When a harvest runs hotter or sweeter, a small run can be adjusted. A pallet-sized run cannot.
There is a texture argument too. Blending in small volumes keeps coarse and fine ingredients evenly distributed instead of separating in transit.
The result is simple: a jar that tastes like the ingredients listed on it, for as long as you are using it.