The cashmere coats sold on Douyin may not have collar tags due to the following reasons:

1. Trademark cutting: Some merchants may cut the trademarks and collar tags on the clothes. This behavior is called trademark clipping. This practice may be to imitate other brands, or it may be to reduce consumers' brand recognition and comparison, thereby increasing their own sales.

2. Illegal counterfeiting: Some merchants may produce fake and shoddy cashmere coats. These clothes may not have the original brand or collar label. This behavior is illegal and consumers should avoid purchasing these items to avoid financial losses and safety risks.

3. Internal sales: Some merchants may sell cashmere coats as internal sales and not sell them to the public. In this case, the product may not have a trademark or label.

In short, the lack of collar tags on cashmere coats sold on Douyin may be due to trademark clipping, illegal counterfeiting, or internal sales. Consumers should pay attention to purchasing regular brand products to protect their rights and safety.