I’m gonna hold off giving a crazy long-winded answer, mostly because I’m not great at typing well-developed thoughts, and because there are waaay more knowledgable people out there.
I would say it comes down to two things for any large bike brand, Specialized is not unique: where and how e-bikes are defined in law, and how much would a brand be willing to dump into product dev to potentially get their hands slapped and/or produce a product that can become a huge liability down the road.
The e-bike landscape is such a wild-west right now in terms of what people will be wanting to/can ride in their area next year, let alone in five years, that bringing a product to market that can be serviced and sold reliably and profitably is darn near impossible. Will throttles be banned? Will there be speed limiter requirements? In AU? What about the US? Europe? What battery tech and regulations are out there?Sure, Spesh, Trek, Giant can bring a relatively affordable model to market (e.g. Globe, Townie Go!), but it takes a ton of time and a category that will demand very little spec change through the product life cycle.
The mobility crowd needs something low cost, adaptable, and serviceable; which are contradictory characteristics when we are talking about getting a global network of dealers accustomed to and confident enough to service the bikes and motor systems without an unacceptable degree of liability for both the manufacturer and it’s direct retail channels, as well as independent dealers of all sizes. As a result, the easiest product to slap a prestige brand name on is a high-end, very categorically-defined (hardware-wise) bike at can be sold at a profit margin that makes the R&D and roll-out worth it.
The buy-in of mechanics and dealers is not only a nice selling point that distingushes the big name brands from e-bike specific brands, but it is the only mechanism for those companies to bring an e-bike product to market. Specialized cannot introduce an e-bike model that does not have mechanic certification/safety design as top priority in any other channel (i.e. direct, via online retailers), and so they must put that money into developing those resources. There’s no other way around it.
That’s also just the mechanics of the bike; the selling of a motorized vehicle is a jurisdictional and liability-laden minefield. In the US, the state of New Jersey just passed a law requiring permitted operation, insurance, and an age limit. How are traditional retailers supposed to deal with that in NJ, but also the bordering states? There are two Trek dealers on the opposite banks of the Delaware river between PA and NJ, will there be liability for cross-state resident sales? Probably not, but do you want to be the indie shop that finds out? Specialized needs to be able sell not just you (the rider) a bike, but first and foremost that shop owner a piece of inventory they can sell - hopefully quickly to an eager, satisfied customer; but at the bare minimum, legally and without excess “wait wait wait, I’m a co-defendent?” risk.
For $5.6k, Specialized isn’t selling you just an e-bike; but a rigourously tested machine that is a low-liability as you can find, with a mechanic that can work on it, and - for good-measure - buying that mechanic’s independent shop a sand bucket to stick swollen batteries into and a recycling contact for disposal down the line - all without employing a single engineer (but a few lawyers) in the whole of Australia.
Lastly, comparing all that to the business model of a direct-to-consumer e-bike brand that has no customer support, dealer interaction, or, increasingly so, technical support of any kind. The extent of that company’s investment is producing a bike with the quality target of “just don’t get anyone killed to avoid the unanimous passage of a Congressional bill called “Kid who died riding our e-bike”’s Law”. That product’s compliance for import to any given country is what can make it to port in three months, with future compliance being tommorrow’s problem. And lastly, any product support and maintanence is fully on the end-user. That is maybe not the $3.6k right there, but definitely $3k.
This is just the tip of the iceberg. There are so many other factors and such nuance in this part of the industry that I can’t really get into, but this might be a bit of a primer of it. I said I wouldn’t be long-winded, but 
. We’re all endurance athletes here - we have a lot of wind.