They can still use the owner-operator model if they want to, and have the vehicles owned by a different entity than the freight company.
But in all seriousness, although I understand that people like to out-cynic each other, over the road trucks seem to be pretty well-maintained. Whether that's the result of safety regulations and enforcement or simple economics (a broken-down truck is not a moneymaking truck) is left as an exercise to the reader, but either way you do not see a lot of barely-making-it or broken-down commercial OTR trucks on the road. That level of poor maintenance is generally the province of private vehicles.
But in all seriousness, although I understand that people like to out-cynic each other, over the road trucks seem to be pretty well-maintained. Whether that's the result of safety regulations and enforcement or simple economics (a broken-down truck is not a moneymaking truck) is left as an exercise to the reader, but either way you do not see a lot of barely-making-it or broken-down commercial OTR trucks on the road. That level of poor maintenance is generally the province of private vehicles.