I teach people how to assemble their own bicycle at my co-op. I cover a lot more than just a basic assembly, because I find a lot of factory assembly sub-standard. For the big brands like Trek and Specialized, maybe that is because the companies are trying to keep the cost low, and rely on dealers to do a proper assembly. I don't know if direct-to-consumer companies are actually any better at providing more accurately assembled bikes out-of-the-box than traditional brands with a dealer network; I cannot say judging by your unboxing video alone.
One way to avoid self-assembly altogether is to just take your online purchase to a bike shop and have them assemble it. Perhaps some shops won't do an e-bike, but at my co-op we do full-service for those that do not care to learn, and at every shop I have ever worked at, we assembled bikes people bought elsewhere. Another option that is available in more and more locations around the country is a mobile bike repair service such as Velofix or Beeline Bikes. Some online bicycle companies even have contracts with these mobile bike shops to have their products assembled, which is smart from a warranty and liability perspective.
