Peanut allergies are very common in the modern world. According to the American Academy of Allergy, Asthma & Immunology, between one and two percent of the U.S. population is allergic to peanuts. If you aren't allergic yourself, it's very likely that you know someone who is. Given that peanut allergies can be life-threatening, this also poses a substantial health risk around the world.
In the past, Texas Roadhouse restaurants featured peanut shells covering the floor, inviting guests to toss shells while waiting for their meals. Nowadays, this tradition has changed. Patrons can still request peanuts, but they come in packets instead of being served loose. This change is largely due to safety concerns, as several lawsuits arose from patrons slipping on shells, alongside health considerations such as germ spreading and peanut allergies.
The check-in desk assistant was concerned about the insect bites on Joseph's leg, which led to a medical hotline consultation that resulted in their denial to board the flight.