Below is a selection of popular lighter duty work trucks. Many times, it isn't about the need to carry a lot of weight , but just enough tools, parts and things to get the jobs done. There are many advantages to getting a light duty work truck compared to a heavier duty truck and body. One is initial cost. It costs less to get the truck to begin with. Another big one is lower cost maintenance because the tires are smaller and less costly, the brakes are less costly as well, you may get the job done with a V6 instead of a big V8.
A perfect example is taking a 1/2-ton pickup instead of a heavy duty 3/4 or 1-ton, adding a commercial truck cap or shell to the back to keep tools and things out of site, add a bedslider to make it easy to access everything, and you're in business! Need more? Add some external power to run power tools, or a compressor for compressed air, a rack for ladders. There are so many creative accessories that can help make a lighter duty truck a real workhorse.
In addition, now the factory has authorized 1/2-ton trucks to be cab chassis models so that optional truck bodies can be installed. Though these won't carry the weight of the bigger trucks, a lot of end users can get all they need to get done and save a bunch of money too.