I do warehousing on a large scale, we have about 16M square feet spread across the country. Very few vendors sites are directly linked to the manufacturers product inventories as much as you would think it is. The tech is out there but its not quite there for most companies yet. We have 40+full time programmers and bought our software vendor to keep up with ecommerce orders. We offer this service to customers, its a premium charge for it. Even when a manufacturer does have capability to provide the data to their retailers , many dont/cant update it in real time on their point of sale portals.
You would be surprised how many "drop shipments from manufacturer" come out of the manufacturers warehousing network, not out of the physical plant that just made it. We are the "manufacturers drop ship point" for hundreds if not thousands of products, yet we dont make anything in our buildings. The video games, home electronics, and appliance manufacturers are way ahead of most other industries in this regard.
the face of shipping and ltl in general has evolved alot in the last few years.