Tobermory is in Ontario Canada...somewhat north of Florida...
I am aware of where Tobermory is unfortunately. It seems like half the population of Ontario makes the trip down to Florida every year for the winter, or as we call it "winter."
I am well acquainted with the official book procedure, as I have to sign the nitrox log a couple of times a day when I am diving while traveling, along with the reason for testing (I am considering buying my own tester for the foreign dive shops where they might not have a back up tester). It was simply an observation that at a half a dozen shops that I gotten Nitrox fills at, from local Tampa areas shops to those down in South Florida and the Keys, that I've only ever filled out the nitrox logbook when renting tanks, everything else is the same as the renters except they never had me fill out the log book. And I've seen the same shops stop the renters and make sure that they fill out the log book.
*shrug* I would think the liability would be the same be it if it were a fill or a tank rental. I wouldn't mind either way, as filling in the log adds at most 30 seconds of time.
My local shop is even more nonchalant as it is more like "You know the procedure and how to work the tester, come into the showroom to check out once you are done and have loaded your tanks."