I probably would have answered this a little differently ten years ago. Times change, and so has this business.
Testing the waters with minimal investment, age, health, and a host of other items have been there for quite some time.
What has changed is a continual downward pressure on rates, how carriers operate, and higher operating costs. Have to remember that most carriers are operating at rates from ten years ago yet the costs to operate are rising. Good used trucks are disappearing and new ones are getting pricey. Priced a new truck lately? Nasty and quite frankly, not too reliable with the EPA junk on them.
The good fleet owner that has a ample supply of trucks and finances can purchase the truck and many services much cheaper than a individual truck owner. Those services go from truck items, maintenance, insurance, financing, to the truck purchase price and beyond. The individual disaster of a wreck, health, or other things can be absorbed much easier with a fleet owner. Why? Continual cash flow that a single operator doesn't have access to.
Relationship with the carrier is another. Many fleet owners run at a higher rate than a single o/o. Sorry, but that is how it is. With less drivers and trucks available, only the fool fleet owner wouldn't leverage his trucks somewhere. Carriers aren't fools either, and adjust accordingly.
Lastly, in our case, I can look at traffic lanes, book freight, and a host of other things that a single truck couldn't do effectively. Bottom line, a driver can easily net much more than driving their own truck. See it time and time again. For folks that have been on EO for say 10 years or better, look who is still here. Might be a thought to ponder.
Good question though.