This person might be a little confused as those beds are definitely not the same length. They might be consuming the mid-size truck 4.5ft bed as the length of that Silverado. I’m being generous to that smaller truck if it has a 4.5ft bed, but the Silverado has a 5.5ft bed standard and also has a wider bed. Specifically greater than 4ft between wheel wells making transporting of standard sized plywood and drywall super easy. Carrying 6 people too is also something that smaller truck isn’t doing, nor is a high towing capacity like 15k pounds. Does the average America need that? Most likely not, but to claim they’re the same is disingenuous.
You can tell the about size by the tire. Considering a standard 5.5ft American truck bed could easily accommodate 4 tires laying down flat and still have plenty of left over space both width and length while this truck seems to struggle with one. Again, 4 tires could fit in the small one standing up, but this comparison is apples to oranges. Both fruits, but different categories.