That feels like something I've seen many times in gas stations but never actually paid any mind to it.
Adding to what Kraco said, a fair amount of people want to have something healthy in convenience. Stocking up on Bananas is cheap and easy way to bring another type of people into your establishment, and potentially get them to buy something else. My store usually gave fruit free to kids too, even though most of the time they didn’t want it.
[...] Maybe the goblin is a sporty one. He actually looks decently fit.
I dunno, slouching shoulders like that suggest he's a bit of a slob. Also, skinny goblin arms don't obviously show much muscle. We'd need to see him shirtless to check for six-packs or kegs to tell if he is fit.