Hauler Career in Farsite accomplish delivery contracts to earn Credits. Their job is to safely move goods between Stations and Planets. Equip your Ship with powerful Modules or hire Fighters to protect you in low-secure environments.
Ingame resources/items are location based. If you need to transport huge amount of resources, cost for you will be much higher and riskier than for player who offers this service.
It might sound unimportant, but imagine carrying hundreds/thousands dollars worth of goods/items, and you get ganked, killed, robbed, god knows what. To prevent such scenarios you want to hire haulers.
Haulers are heavy armored big transport ships that can sustain some damage and escape scenarios which would destroy most of other ships. If hauler you hired gets destroyed, your goods are ensured and you lose nothing. Your goods are secured by smart contrating service with hauler. Hauler must offer collateral to you, in case his transport ship with your goods gets destroyed.
Contracting with Haulers is done by ingame solution, where you need to be careful what contract you are agreeing too. Example. You want to transfer 100,000 Credit worth of resources. Hauler asks 20,000 for that service, but offers only 30,000 compensation if his ship gets destroyed. That means, in this case, hauler is more motivated to destroy his own ship and steal your goods, since insurance is only 30% of cargo value. So, you will need to search for haulers who offer 100% insurance on transported goods.