1. Economies of scale are the only way to build a budget car.
2. The incremental costs of adding features are nearly zero. The vast majority of price comes from the basic costs of building a legal vehicle.
3. Buyers generally won't reject a car for having features they don't care about, but they'll frequently reject a car for lacking a feature they deem important.
4. Buyers have different preferences.
In order to sell at a low price, automakers have to sell as many as possible to hit massive economies of scale. In order to sell that many, they need to please a huge number of buyers, which means they add a whole bunch of cheap features to satisfy as many buyers as they can without cannibalizing their higher-tier offerings.
The other side of this is the price point that western OEMs can actually hit with economies of scale has climbed significantly in recently decades, in part due to inflation / wage pressures, but mainly due to massive institutional inefficiencies. Mary Barra's compensation alone adds several dollars to the price of each GM vehicle. Legally mandated dealer margins and fees add tens of percent to the price that consumers pay. The inefficiencies of spreading production for tax purposes across state and international borders adds more cost. So on and so forth, and the market feedback mechanisms to correct these issues are intentionally hampered by policy decisions to favor the current status quo.
Change in the market needs support at the regulatory level.