Welcome to the Forum @Katabalu.
This subject has been discussed previously here. Same objection as you.
Don't worry. By the time you receive the shoes, if Jane had, let's say, athletes foot, the fungus probably would be dead. It needs a warm, moist environment to survive; however, someone can get it from shower floors, swimming areas, etc.
Yes, I know, it's the thought of buying shoes someone tried on with bare feet that could be dirty or had a fungal, bacterial, or viral infection, such as plantar wart that occurs on the feet.