It's possible for someone to get sick when eating fruit or vegetables that are unwashed if you happen to catch something from some bacteria that could be on the fruit or vegetables.
But from personal experience I would say the risk of getting sick from eating unwashed fruits or vegetables is very low as when I was a kid I used to pick apples off a neighbors tree and eat them right away without washing them first and I'm still alive and healthy.
I have my own apple tree and I still pick apples from the tree today and eat them when I'm outside picking other ones.
The ones I do bring inside I do wash to store them but I get hungry while outside and just eat the apples right off the tree and I've never gotten sick from it.
So it's possible to get sick from the unwashed fruit or vegetables but the risk is so low that I wouldn't worry about it.