I could argue that wizards might have been a little apprehensive about walking into the lion’s den when Voldemort was in power, and after his downfall people thought he was dead. As for Harry, I don’t know.
As for your guess, I’d reply, then why do wizards worry about owls being intercepted and the messages falling into the wrong hands? And why does Hedwig sometimes take so long to return from delivering a message to Sirius, showing signs of exhaustion and exposure to the elements?
I always thought that the owls knew where people were, or maybe shared information amongst themselves. I seem to recall a time when Harry ended up at The Leaky Cauldron, and Hedwig was there waiting for him? “Smart bird” somebody said . . . He was still ont he night bus when she headed that way.
As for following, you’d have to be one heck of a seeker, as the owls would likely take evasive action, flying through steeples and tree branches and such. Why else would wizards hide far away? With all their powers, hiding next door would be just as plausible - unless you were afraid someone might keep up with an owl long enough to find you.
Owls can be intercepted, but they can’t be practically tracked. If Harry in Hogwarts sends a letter to Sirius wherever-he-is, and the owl is intercepted in, say, Portugal, all that tells you is that there is a route from Hogwarts to Sirius’ location that passes through Portugal. You don’t know how far away Sirius is, and you don’t even known that he’s on an extension of the same line: Maybe the owls just fly that way because of the patterns of prevailing winds, or the like, and swing far out on a different bearing once they’re over the Atlantic. You could in principle tail the owl on a broomstick, but I’m guessing that the speed and/or endurance of the broom (or its rider) doesn’t compare favorably to an owl (altitude might also be an issue). And there are technological means that could be used to track an owl, but the wizards aren’t up to speed on those, and they wouldn’t even work in many locations.
Plus, I suspect that most of the owl interceptions were very close to one of the endpoints. It’s a lot easier to monitor, say, all of the owls coming into or out of Hogwarts than it is to do so for all the owls in the British Isles.
I’ve come to the conclusion that they teleport (or apparate, if you’d prefer). So you grab your owl, chuck him out the window and he flies out of sight, then POOF, appears out-of-sight of the target and completes the trip.
Trust me, this is one of the smaller plot holes in that series, indeed even in just that book. The ending reveals that a 13-year old girl was given a time machine so she could take on extra classes, for Christ’s sake.
The real question is, why has nobody in the Harry Potter wizarding world tried to reverse-engineer the tracking magic in the owls to make an unbeatable tracking spell? But that just gets you back into the remarkable lack of curiosity as to how magic actually works, and the poor world-building skills of JKR.
Hogwarts contract with the Owl Union prohibits tracking messenger owls. Last archmage who pissed them off ended up in a concrete support for a Quidditch stadium.
Maybe owls enter hyperspace en route to their recipient. But how then would they be intercepted? Sometimes they have to pop out of hyperspace to eat and shit and stuff like that.
Know what? I love the camping stuff. It’s a little slice of realness in such an obviously unreal situation. I’ve been that teenager. I’ve taken that trip. I even love the interminability. Makes me feel like I’m suffering through it with them.
In the fourth chapter, Harry figures out how to arbitrage the difference in the relative valuation of gold and silver between the wizarding and muggle worlds.
Wow! That’s some serious action there! If there’s a chapter where he figures out how to convert actuarial tables from Middle Aged Muggle to Ancient Wizard (and shows his work via long division and calculus), then I’ll click that link!
No, it never gets that technical. It’s both cerebral and keeps itself accessible to smart youngsters.
The main point is that Harry is as smart or even smarter than Hermione in this, and spends time figuring things out. He even exploits a time turner. (And even accidentally got limits placed on his own by showing all the flaws of giving students one.)