It is not unusual for a motor to not get registered in a busy dealership. Someone has to take ownership for doing it and usually it is the sales department's responsibility. Not to make a generalization....but the sales guys don't like to do paperwork....they just love to talk and sell. Registering the motor takes some time and unless they get paid for it, it may slip in the cracks. If the dealership has a routine setup that it is checked before the sales guy/gal gets paid, then it will get registered.
Likewise, in a small shop, where everyone does a little of everything, it turns out the the largest fire gets put out first and the small detail of registering a motor gets stuck in the drawer to be done later. Sometimes, later never comes.
So...I do not think it is a conspiracy or anything like that....."stuff happens".
Mike