The cycle rickshaw, which is a variant of a cargo bike is quite common in Asia. The price for a new one ranges from $100-500. Meanwhile, a bike with elongated rear rack, e.g., a longtail cargo bike (barely counts as cargo bike) can cost $1,000 in the West, and that is the entry level “cargo bike.” A front load cargo bike costs $2500 and upwards. An Urban Arrow ™ cargo bike can cost a whopping $6-7k.
At least one small reason is that Americans like lots of features on their bikes. Cycling in Asia is a simple mass produced mode of transportation meant to mobilize a people vs in the west it’s a niche hobby funded by do gooders and urbanists who can afford good but expensive components
I don’t think this rings true in like central europe, the netherlands and such, where cargo bikes are still pretty expensive