Earlier quoted context omitted.
I still bring a 3ds in my bag when I fly just on the off chance I get a street pass. Sure I know you can run your own relays at home, but it was always neat finding a random person, more so when you had a repeat.
I don't think the home relays have worked for years. Nintendo shut down the backend servers at some point. Nintendo had a deal with someone (att?) that all their free wifi hotspots would work as street pass relays. The way this worked under the hood is that your 3ds would see a wifi network named attwifi and then check the mac address of the ap, then it would report to Nintendo backend "hey, I just passed near mac xx…
Still, was a cool idea!