Why is KuCoin not allowed in USA?

Could you please elaborate on why KuCoin, a popular cryptocurrency exchange, is not permitted to operate in the United States? Are there specific regulations or legal constraints that prevent it from serving American clients? Are there any potential risks or concerns associated with KuCoin's operations that have led to this ban in the US? Furthermore, how does this affect US-based investors looking to trade cryptocurrencies on KuCoin? Is there any hope for a future change in policy or regulations that would allow KuCoin to operate in the US?