Because production is higher than demand - it has to be and will become even more so as the zero emission mandate increases. Manufacturers have to sell a certain number of electric cars irrespective of demand for them in order to be able to sell conventional cars. If demand fell to zero overnight they'd still have to register a significant volume anyway, even without a buyer.
You can see the effect of this supply/demand imbalance on the used market, it is the reason behind the huge depreciation we've seen over the last year.
It's the entire reason why we even have the zero emissions mandate - if demand for electric cars on its own would have been sufficient to ensure the right volumes were being sold into the market, there would have been no need for the mandate as the market would have done it anyway.
This will depend entirely on your view as to whether the market should be controlled and directed by the government or dictated by the free market or not. You can make a case for either of those.