First, the tile looks really good. Second, I have been in your shoes and the lesson learned is to always go through the tile before it is installed. Third, the issue is surprisingly common. I don't know why tile stores don't put giant signs in the showroom that say the tile you receive may be different than the display.

In your shower, I can see a few tiles that look similar to the display tile. But, you're right, most of them have more veins and the display tile isn't really representative of the box.

My tile as displayed at Home Depot.

This is what came in the boxes from right under the display. I never opened them, never expecting them to be so different.

I hated them on sight and had the installer rip them out and replaced them at my own expense. And I learned to always go through the boxes of tile.

The time to talk to the supplier about problems with the tile is before the tile is installed. Look at your receipt; it likely states that once the tile is installed, you are out of luck.

Hi Patty-

Well, I too like the more subtle look, but what you ended up with is beautiful too, and looks just like real marble.

You have a little less flexibility in how you do the rest of things in the bathroom, I wouldn't paint the walls a color like light blue, whereas you could have done that with the lighter tile.

But if you were going with a white or light grey anyway, it's okay.

Just don't go to dark on the floor tile, and around the edge, or use dark towels.

In the vast scheme of things, it's not worth the energy to get worked up over.

Maybe you could get a $ credit to be used for something else?

She mentioned that there is variation in marble tile

She's describing it as though it's real marble, which it's not, so she either doesn't understand her product or doesn't remember what she sold you.

To me it looks like it was installed a bit clumsily. True, there's two tiles with identical patterns installed side by side, but I see a third one with that pattern touching one of those other two (making three of the same that touch).

Below that group there's two in close proximity where the pattern was simply flipped on one. Even though it's flipped it's obvious.

If you could fix those it might look a lot better. I would ask for three tiles to be replaced - I'd replace two in the upper half (of the three that all have the same pattern) but I'd have them replaced with pieces more similar to the sample tile pattern to lighten things up. On the lower half where the two aren't adjacent but awfully close, again, I'd replace one so it looks more random.

If you get to this point pay particular attention to the actual pattern choice, the actual piece of tile to be installed. I think you can rescue this look and be very happy with it. In fact, when you really look at the whole picture and consider it thoughtfully, there's at most four (maybe five) individual tiles that "darken" the look from the "lightness" that you expected. You could replace all of those and be even happier.

Take a deep breath. You can fix this. I like it and think it's very pretty.

I'm sympathise, this is an unpleasant situation.
The tile seems busy, and my preferrence would have been the sample, as yours was. However it's not all bad, can be lived-with if you decide to.

Though it is true that any changes at this point will have to be at your expense. And the reason for this is that, with everything, installation is acceptance, regardless of whether the product installed is what was ordered or not. Regardless of whether the consumer was there or not, as the consumer is responsible for accepting and approving the delivered product, or arranging for someone else to do so

"people... can't believe that the tile installed is the same..."
There's the key. If the tile was not the same, or in any way not satisfactory, it should not have been installed.

"the supplier insists that it is."
It may be so. Variation in tiles exists, sometimes to drastic extents.
Samples aren't always from the same batch as the current stock, samples might be showing the extreme of variation, and though it's poor practice to have poor representative samples, the supplier is not obliged to replace installed tiles on those grounds

"So, now that a week has passed, I don't hate the tile as much as I did a week ago, but tbh, I still wouldn't pick it... What would you do, would you fight it?"
No, and I wouldn't advise you to either, unless you are fully prepared to pay the full cost of the tiles, labour, time, etc. A silver lining is that you don't hate it that much

Another point is the variegation, but if you can't see the pattern don't look for it :)

I would replace the tile left third from top and use a light grey grout it will look much calmer I have a similar tile as your sample the before and after grout look so different. for what it is worth I like your tile better than mine. I also matched my shower to a light grey plank floor.

Patrick has an easy fix and one that I noticed immediately--remove the three identical tiles. It looks like he just placed them in the order that they were in the box. No tile setter who cared about his work would have placed those together. It defies common sense. They should change it and not charge you a dime.

Why remove three...just remove 2, leave one and make sure the new ones are different than those surrounding.

Because she doesn't like the gray. There's one in the bottom corner too. It seems more distinctive than the others so it's best not to repeat them on one wall.

I agree your tile setter needs to fix their mistake and fix those 3 identical tiles. Your eye goes right to it. Then make the grout light and it will be gorgeous.

Thank you everyone for your comments and suggestions, thinking I will ask to have the two tiles replaced that are side by side. Will post when it's all fixed and grouted. :)

Ask to have three of the matching tiles replaced. There is a fourth one in the bottom right corner of the same wall. Choose tiles with a much lighter pattern like the sample. Once those three are gone the shower will look much different.

I see a pelican in the second row. The second tile forms the neck and the third tile is the head. So I'd remove the three heads. The one on the bottom isn't very noticeable.

You know there's some imagination around with designers seeing pelicans...

A few years ago peacocks were a popular design statement. Maybe pelicans are next!

I too am looking for tile. Sometimes you are fortunate enough to see the sample already installed on a showroom wall, sometimes not. So I go the manufacturer's website and you can usually see pictures of rooms done in the tile you are considering. You can then see if you think it's too busy. Also remember what Dragon fly posted above about the shade variation (V1-V4) so you know what to expect.

If you decide to have individual tiles removed and replaced, ensure the tile setter doesn't damage the waterproofing which should be underneath.