Due to differences in their diet.
Cockroaches feed on human food and food scraps, as well as pet food. This allows them to carry bacteria and viruses on their legs that may be present on food.
Spiders, on the other hand, show no interest in human food, which makes the likelihood of their involvement in the transmission of pathogenic microorganisms extremely low.
Furthermore, their limbs interact with webs that have bactericidal properties, which further reduces the risk of carrying microbes.
