One reason why Terry is because some people, won't wash their hands, and if you ever watched a kid wash their hands, it can be useless. So, they go to the bathroom and then, go to the kitchen get something to eat, they carry the matter everywhere they go. I seriously, think a study should be done testing the steering wheel that would be amazing!
And, just imagine, how many people eat while driving... yuk. Can you imagine the germs on that steering wheel? Especially in the summer heat.