Well there are 2 things besides prices
#1- No foreign maker has an HD truck. Many trades require an HD truck.
#2- The Domestic trucks are better quality when it comes to the frame and drivetrain mechanicals in terms of strength and durability.
So bottom line is, while the domestic trucks are cheaper, they are engineered to have the shit beat out of them when it comes to towing, payload and off road. The Tundra and Titan are not.
If I am thinking he is the right guy, Snowflake works in the oil fields on the pipelines. Many of the trucks you see out there are welding rigs, which have to haul 2000+ lbs of welding equipment, so typically you see 3500 dually welding rigs.
The Tacoma on the other hand is a different story. Could possibly be the most durable truck there is aside from towing.