The risk for anal sex, if other factors are equal, is greater for a receptive partner compared to an insertive partner.
The surface area inside of the anus, is larger than the surface area of the penis.
The risks of tears to the anus during sex is greater as the membrane on the inside of the anus is more delicate than the skin on the penis.
Pre-cum and cum will stay in the receptive partner for longer than the insertive partner is in contact with rectal tissue and mucosa.