There is no secret to why riding in cars is so difficult for people who have hearing loss. The environment of a moving vehicle is a cacophony of sensory stimulation; road and engine noise, wind noise if the windows are down, radio blaring, lively conversation, fluctuating light, and distracting scenery. It takes a lot of concentration for a HoH to hear and respond to speech in a car.
Those who have hearing loss do not corner the market on being anxious about traveling by plane alone. Many people who have no disability or barrier fear travel. However, the inability to hear announcements is an added anxiety and requires more presence of mind for the HoH to stay on top of important information they need to know.