Bosch and its name brand competition has a good thing going. By one European retailer survey,
Bosch alone had 69% of sales. That's an oligopoly, if not a monopoly, according to antitrust definitions. It's more profitable to get a small cut of oligopoly profits than it is to try and blow up the oligopoly, if the oligopoly can compete with you even at lower prices, which it can. Especially in an environment like with big bike brands and component makers, where the ecosystem is fairly stable and interrelated, and pissing off your colleagues can be very risky to your long term success.
They command high markup on their goods, and they can use some of that profit to keep their dealers and brands happy, and thereby prevent price competition from entities that would otherwise be their rivals. The big brands have no incentive to engage in serious price competition, no more than a few percent. Internet startups do, but they're in many ways not competing, because they don't operate in retail stores mostly, have much less of a footprint in Europe, and also just make lower-end bikes in general.
The few companies that might change this mold, like Canyon, show little interest in the lower end of the e-bike market, and are anyways still a brand that's not going to make their own parts. Also in the US, they seem pretty focused on high end bikes ($2k+ even for analog ones).
How could things change?
A motor maker like Brose is interesting because their motor can be used with third party batteries. If Brose or other motor makers keep their battery interface open, AND reliable low cost battery suppliers emerged, that could upset the apple cart. Brose doesn't seem to have much market share, while Bosch does (I don't know about the other makers and their battery interface standards). For battery competition to arise, the battery OEM would likely need a lot of volume to compete on price effectively.
And even then, the case for Brose specifically as savior may be weak, since they now also make their own batteries, and may eventually forbid third party batteries in new models. Plus, it's not clear that consumers are even aware of the problem, because you aren't buying a battery separately when you buy the bike (I doubt more than 10% of customers buy a spare upon purchase of a new ebike), so a brand has little effort to go to all the trouble to use batteries that are cheaper on the post-purchase retail market, a cost that the end-consumer won't experience until ~5 years later.
Juiced, for instance, was selling the same battery for $500 and $1,300 - $500 if you bought a second battery for your Hyper Scorpion and $1,300 if you bought it separately, same battery. Usually though it's not so obvious.
Also, the battery prices you show are based on non-e-bike sources where costs are significantly lower due to bulk sales, especially Chinese e-buses which have even lower costs than cars.
People who always focus on lowest cost will never be persuaded by value factors. Their cheap stuff breaks down more often adding to their suspicion of all manufacturers and making them feel like "they" are all out to rob and cheat them.
Banging your head against a wall only feels good when you stop
People who ignore cost fundamentals will often defend oligopolistic pricing, because they think prices far in excess of cost are essential to quality. Before Toyota brought out Lexus, German brands say luxury cars had to be far more expensive and less reliable than what Lexus offered. And more bluntly, Alaskan's apologia ignores the *trend* over time of prices declining, while Bosch et al batteries haven't.