Regulated, time-limited, and unforgiving of a documentation error.
Pharmaceutical and medical cargo carries a regulatory burden no other sector matches. NAFDAC registration and permits govern what may be imported at all, and the paperwork has to be right before the goods ship — a NAFDAC issue discovered on arrival is not a delay, it is frequently a rejection.
Time compounds it. Product with a shelf life loses commercial value every day it sits at a port, and cold chain cargo can lose all of it. That makes clearance speed a product-integrity question rather than a cost question, and it is the strongest argument for handling documentation pre-arrival rather than on landing.