There are companies which work on high volume sales, instead of high profit margins.
I don't know anything about these specific bikes, or how good they are.
One site says 36V 7.8Ah Battery.
When I get an ebike, I will probably buy a kit, and put together my own. If I did buy a complete bike, I would buy an inexpensive one. Not all expensive things are good, and not all inexpensive things are bad. If I found it was not good, I would buy something different next time.