These questions are getting more broad, and the answer to all of them is "it depends on the job".

Light duty trucks and box trucks are also commonly seen at various job sites. It's also quite common to see a truck pulling a trailer – and there are lots of different types of trailers. Choosing the right tool for the job just depends on what the job is.

Here's one example from a job I once had, long ago. If you fill one of these with water, it already exceeds the weight limit of the little truck on the left:

And, depending on the size of the job, some jobs would require more than two people to get the job done. Those crews would get the trucks that have backseats.

Sure, you might be able to find smaller IBC tote tanks and just use more trucks, but that would be pretty inefficient, especially if each truck/crew has to drive hundreds (or even 1k+, in some cases) of miles to reach each job site on its route.

We also used box trucks in some cases. Some job sites required using two IBC totes, which did not fit in any of the company's pickup truck beds. For those routes, we rented box trucks. But for one IBC tote, a light duty truck is too small, and a box truck is too big.