You never know if you're going to get ripped off, maybe with fake money.
There's also the question of people who don't show up to collect. I often wonder how desperate someone would have to be to sell something online to a stranger for $2, then wait in and hope they show up, either letting a stranger know where they live or spending money on gas to meet somewhere neutral.
In my area several people do porch pickups where you just take your item and leave the money in the box. I wonder if they get ripped off by people who take the item but don't leave the money, or who take other items too. Even if you have a camera on the porch it's hard to imagine the police taking much interest in a complaint that someone took the $15 item they agreed to buy and only left $10, or that some blurry person wearing a mask (can't be too careful around COVID, or when there might be a camera and you want to justify covering your face) took an item you left out for someone else to take.
It's not a big deal but there are always the idiots out there. Years ago I sold a car on the marketplace. I took photos of it from just about every angle imaginable without crawling underneath it, pictures of the inside of it, the dashboard (showing the mileage), each of the tires to show the condition. Then some idiot asked if I had more pictures available, and didn't respond when I asked what he wanted to see that the pictures didn't already show. I didn't have to deal with this particular issue but I know people who have had all sorts of sob stories of why they should give away their item and deliver it to someone 200 miles away because - boo hoo - life is so hard on them and they just can't catch a break and they need it soooooo much more than you do.