Am I going to start my own company selling these? No, because to do so requires a capital investment into a factory, and selling the ESC/BMS will make a pitance compared to the ongoing hassle of dealing with customers.
There is a vast chasm between 200$ hub and 1500$ hub, that's nearly an order of magnitude. The 200$ hubs are heavy as hell (actually, the quality on HUBS is quite passable even on the cheapest ones in my limited experience), the 1500$ Maxon hub will take barely the power desired for a DH bike and is retardedly expensive. I really don't see the complication in my thoughts, I want an MXUS 3k turbo with a 12mm through axle and a weight loss plan, and would gladly pay 500-600$ for it. I would also gladly pay 500-600$ for a hub like the Maxon to put on an XC bike, but 1500 is just ridiculous.
The BMS is a safety issue, they should not be sold. We have safety standards in the EU, USA etc, and lithium battery controllers that catch fire in normal use are not acceptable. Purchase was via Amazon, not Aliexpress. It's not currently clear to me where one buys a decent BMS off the shelf; hence I have designed my own.
As you say, it requires capital investment. Regardless, expensive (Maxon) or inexpensive (Chinese mid drives) both have capital investment so they both have to recoup costs and make a profit. If your "wish" was so easy, the market would be flooded.
Amazon, AliExpress are just e-commerce platforms. They are NOT entitled to enforce local laws. If you want safety, then visit your local e-bike store (yes, pay more and support your local business) and they will provide you with a reliable BMS/mid drive under warranty that conforms to local laws. If you choose to buy online then you are doing so at your own risk...simple cost/benefit analysis right.
For people who don't know, testing products and filing applications for legality costs money....this work is not free and needs to be recouped. For example, TUV certification in Germany is process and cost intensive. Many small manufacturers that produce solid products choose to not sell in that market because the markup for their products (to re-coup the TUV) would make their goods too expensive.