I just got certified, so I have zero experience renting SCUBA gear.
However, I play in some jazz groups and rent a lot of other gear. If a fuse blows, it's basically a wearable part and I need to go into my bag and pull out a fuse. If I don't have a fuse, I need to go buy a fuse. What I don't do is whine to whoever rented me the gear that a part that is designed to wear out worn out.
That said, I would hope the shop would remind you at checkout to see if you need o-rings, silicon lubricant, or any other repair parts necessary to properly service the wearable parts of the gear you're renting.
But when all's said and done, there's no way the shop can know if you used the tank or not. It's possible to fill a tank away from a dive shop.