Why are young children prone to ear infections?

Anatomy: The quick answer - anatomy. The eustachian tube is more floppy and horizontal in children which prevents adequate drainage and ventilation of the middle ear. There are environmental factors like increased exposure to viruses (day care setting), etc. That also predispose children to ear infections.

Eustachian tube: Young children have eustachian tubes that are less developed and at a different angle than adults. This makes it more difficult for children to equalize the air pressure in their middle ears vs. Outside air pressure. This difference makes it more likely for them to get ear infections.

several factors: Young children have less developed immune systems and the eustachian tube that allows fluid to drain from the middle ears is smaller and more horizontal, so it does not function as well. Young children also are exposed to other children with illnesses and are notorious for not having good hand hygiene and thus transmit illnesses more readily.