U-Haul trucks are the scariest thing on the road.
There are three reasons you should pay a lot of attention when you're driving anywhere near a U-Haul:
1. Most people are used to driving much smaller vehicles. Driving a large, boxy truck is challenging.
2. U-Haul does a terrible job maintaining their vehicles. They just barely keep them running. One could fail at any moment.
3. People driving U-Hauls are generally in the process of moving, which is stressful and distracting in its own right.
Put these together and you end up with someone driving a large, unfamiliar, poorly-maintained vehicle while stressed out and distracted. Give this person a wide berth.
This doesn't apply anywhere near as much to other truck rental companies. Most do a better job maintaining their vehicles and are, in part as a result of that, more expensive. That means that the people renting them did some research and chose to pay more for a better vehicle from a less recognized brand.