Why am I finding so few items in the wasteland?
I would have to agree with @Nelson above -- I think this is just bag RNG luck. I've had several instances where the same level 50 guy goes out and finds tons of stuff, and others where he finds almost nothing. IMO the only recourse is to drastically increase your sample size and send the same guy out lots more times and see what happens. If it's 100% nothing after many attempts, I'd start to think it's a bug, otherwise, blame the RNG.