Yup. You can grab any unencrypted data passed between the user's browser and a server literally out of thin air when they're connected to an open access point. You sit happily at the Starbucks with your laptop, sniffing them WiFi packets and grabbing things off of them.

Oh and you have no idea what the myriad of apps you're using are connecting to and whether that endpoint is encrypted. Do not underestimate the ability of firms to produce software at the absolute lowest cost with corners and walls missing.

If I was someone who was to make money off of scamming people, one thing I'd have tried to do is to rig portable sniffers at public locations with large foot traffic and open WiFi like train stations, airports, etc. Throw em around then filter for interesting stuff. Oh here's some personal info. Oh there's a session token for some app. Let me see what else I can get from that app for that person.