Why r yt people so weird?

For some reason I remember this time I went to Myrtle beach in South Carolina this year for spring break. So me my cousin and god sister get in the water minding our own business and this white lady comes up to us and say "I have a mixed child but I didn't know black people do this type of stuff". My god sister my cousin and I look at each other like tf u just say to us. So we replied oh really yeah we do. So then my auntie comes up to us and that lady says it to her and my auntie burst out into laughter. A few minutes layer the lady teaches us how to ride a wave with our surf boards. She was nice just made us feel super uncomfortable