I owned a trucking company and my family owned a freight brokerage business.
Trucking is a hard lifestyle, especially over the road. The job is physically demanding and there are a lot of ways to do it wrong.
Owner / operators and small trucking companies are, in some cases, like sharecropping. You don't make premium money, that's taken off the top through a series of intermediaries / brokers. You have to buy sub par equipment, because it's cheaper. You can't pay your drivers as well and often times, you do so in cash, which eventually bites you. And to boot, the business is very capital intensive. If your customer pays you in 30 days, and you run coast to coast, it could costs you 1100 gallons a week (3000 per week) and you don't get paid for 5 weeks (15000). Add to that cost of maintenance, insurance (650-800 per month - physical damage, liability and cargo), truck and trailer payment ($2000 per month for something newer, but not new, that you wouldn't mind living in or), you have to eat, your cell phone, oil changes ($150 per 15-25k miles) and the 1.25-1.35 per mile you earn, doesn't go all that far. But don't worry, if you need an advance on your shipments pay, for fuel, someone will give you up to 50-60% of your cash, maybe even a little more, for 1-2% or more of all the money you're due. And if you want to get paid faster than 30 days, you can get paid a day or 2 after you deliver and turn in the paperwork, for another 1-2% of the total amount you are due.
One truck shops or small companies can't service the needs of most shippers, so shippers choose big trucking companies or 3pls to manage their transportation. By the time a little guy touches a Bill of Lading / rate confirmation, the shipment can be double or triple brokered, each hand passing paper taking 10% off the top.
On top of that, there's huge theft. Gangs steal tires, cargo, trucks and drivers sometimes choose to transport drugs along with whatever you're asking them to haul...if you are in the business long enough, the stories are epic.