I suppose it's possible it got delivered to the wrong address, if it wasn't the normal UPS guy. If it was an inside job, then the only solution is to stop using UPS, which doesn't sound practical in the long run.
I don't live in the city, in fact I live next to a tobacco farm. However, I'm not really in a position to leave my apartment unlocked, nor do I have a secure location for delivery personnel to utilize. Requiring a signature is the least I can do for now, other than refraining from ordering from companies that don't offer USPS as an alternative.