[hunter2_]

Walking around isn't usually a big deal until told to leave (verbally or by way of conspicuously posted signs), since that is a prerequisite to trespassing. Otherwise, delivery people would operate in a gray area which would be very problematic for them, since not all deliveries are requested by the recipient/owner.

However, although you are free to walk around in search of the front door, you can't start eating the fruit off the trees. Perhaps that's the better analogy: the trees are happy to serve up a delicious treat for anyone requesting something of it, but that doesn't mean the tree sets the rules. Just because fences preventing this are popular doesn't make them compulsory.