Besides the marked-up cost of standard distribution, the number of times a firework is transported before reaching your store greatly increases the likelihood for mishandling and damage to occur. Standard distribution importers accept this fact, when thousands of pallets are being swapped between different trucks and warehouses, accidents are bound to happen.
Less shuffling around from warehouse to warehouse greatly decreases the chance for your fireworks to end up damaged by the time you receive them. Less handling means less duds and product misfires for your customers.