can't fed-ex just google-maps it? seems that would be a probable solution if the address isn't clearly marked on a house, or behind a large tree or fence...
and those UPS guys are doorbell ninjas, i swear. they literally dropped off my newegg stuff, rang the doorbell, and by the time i got to the door to praise them, the truck was nowhere in sight!
GPS is good up to 35'. That could be 8 houses where I'm at currently. GPS is triangulation from low earth orbit. In rural Kansas, sure it's close enough. My driveway was a mile long and the only house for 3 miles. "that must be it".
UPS and FedEx need house numbers on the front, obstructed or not. If it's up, a good driver will see it or just know it. A new driver won't yet. Maybe the UPS driver that actual does your route took a week off. They have like 200hrs to burn a year or lose it (and you get more money by taking time off than the taxed payback and still work). Fill-ins don't give a crap about the route...it's not theirs.
My UPS guy rocks. We'll BS all day, and made my path the last on the list due to my hours, and the way we like to mingle before they go home. My last build was delivered in what resembled a wicker man in my front yard. Took the time to make me smile. A+++