Engine assemblies for use in the final assembly of complete vehciles are test run at end of the engine assembly to check for defects and compliance.
The engine is once again run at the end of final vehicle assembly to test and generate the required FED (and state in some areas, like 'Kalefurnia'
) documentation for emissions requirements to submit to the agencies.
These test cycles, along with the formulation of the oil used in assembly allows for the engine to get a good start in life
The driving and cycling during the delivery and first few drives takes care of the rest.
Hardly anyone reads the manual when they buy a new car anyway ...
Most 'crate' engines are assembled and maybe spun cycled to test for problems, but not fully tested by firing them up and running them in.
You are required to install the needed lubricants and cycle the engine properly to get the best life out of it.
If you don't ... oh well, it will still probably last through the warranty period
BTW - I know you are 'supposed' to take it easy on new cars to help break-in the engine.
But in 1977 I picked up my new 1-ton 4X4 mid-day on a Friday - drove it @4~5 miles to my shop - hooked up to a 9000# three axle race boat trailer and towed it several hundred miles at @70~80 mph to get to a race by morning.
Dam trucks original 350 only lasted @318,000 miles