You will get used to each different faucet and be turning each of them the 'correct' way without thinking about it in no time.

But is there a default correct way?

I found this in an old article: The Uniform Plumbing Code specifies that faucets "shall be connected to the water distribution system so that hot water corresponds to the left side of the fittings." I think your tub was installed correctly. I had not had to think about this because I use single handle faucets. I think one of the plumbers with more knowledge may be able to provide more clarity.

It's not about where the hot is. The hot is on the left side in either case. It's which way the faucets turn.

Thanks. That's what mine do now.

Repeating the motion at my desk, I can see a logic where the left handle moves counterclockwise and the right handle moves clockwise. So each handle function differently. This would make sense the the type of four point handles that you have. For plat handle, i think they behave in the same way, the left handle moves counterclockwise and the right handle moves clockwise. Think of two flat paddles opening towards each other to get water. Watch this video of the pfister faucet with paddle handles as an example. Go to 3:09 on the video. It is easy to fix on your tub since it is the handles it should not involve the valve but I am not sure.

My bathroom sink faucets are currently the opposite to those of palimpsest, both turn away from the middle. The cold was different until our last plumbing visit. Took us months to get used to the new direction.

When I had separate hot and cold tub faucets they turned up and out for on...like socal's and opposite the sink. I wonder if it goes back to older style valves where it was probably easier for people to get a tight Off by pushing away from themselves or down...dunno just guessing.

In the link homepro01 provided, it shows a lever faucet, so it makes total sense that the levers pull towards yourself to run water. That's the same as what I have now, even though mine are not levers. It's as if the manufacturer uses the same valves for lever or cross handle, in the case of my bath, but not in the case of my sink.

My bathroom sink has cross handles. Both faucets turn counterclockwise.

Both turning the same way is most unusual. I think it's an older style way.

It seems that knob and cross handles normally go in the same direction as large lever handles to keep things consistent. (In the manufacturing sense) While sink faucet levers tend to be "on" when they are pulled forward (pushing back would often hit the backsplash), tub levers generally turn in the direction so that "off" is where the lever is in the lowest position so that gravity can not have the possibility of turning them on.

In my case, the bath faucet handles are on the deck of the tub, as pictured, so there is no gravitational issue. What I am learning here is that there seems to be no consistent way to do it. Different context and manufacturer means different knob turning direction for off and on. So there you go.

Your situation on the tub almost begs the question of whether the hot is supposed to be on the left when turning on the water from outside or inside the tub ;)

Well, it's definitely on the left from inside the tub.

I was just being facetious. Hopefully, it doesn't keep you up all night. ;)

The humour was too subtle for me. :)

Since we are bilateral symmetrical beings, I think it make more ergonomic sense to us internally for opposite pairs of things operate symmetrically, or as mirror images of each other.

Totally agree, but there are still two options.

David Fine, if the faucets are now labeled incorrectly, you may find that the "button" that says "hot" or "cold" can be popped off of the handles and popped back onto the opposite one. I have purchased Sign of the Crab shower fixtures that have the white porcelain button, and then ordered buttons that say "Shower," "Rain Head," and "Hand Held" so that I can know which control I am turning on or off. So they must pop on and off. Maybe yours do, too.