Obviously you learned to get a true sample of the grout not the color card. Show some pics as it is tough to judge how off it truly is.

I should definitely have requested a test board. What now though? Continue with the rest of the floor?

Dig out the shower floor grout, if at all possible. Do NOT do that shower floor, or the rest of the bath floor until you have the color resolved. Grout virtually always dries LIGHTER than a sample

That means an ACTUAL sample, chosen in person, and a test board. You do not choose grout online. Period. And you do a "test board"

Why on earth would you "continue" and compound a not great look?

How about a picture form a bit further back as I am not certain that it is that awful from the picture you have posted.

It isn't awful, it's just not what I intended. Since that tile is offset, I think some people would actually choose to highlight it. I wanted a seamless look though, and that isn't what I have now. If I don't have the contractor rip it out - what are my choices? The other thing I'm thinking is that the "color" of the glass shower door may also "distort" the color of the shower tile and grout....

Grout colorant can be used. But if you want uniform grout color with the other tile then you probably want the tile setter to continue with this grout and then color it all.

That is what I am afraid of...Does the grout colorant look messy when it is applied?

Never applied it personally but I would assume it could be if you could not color within the lines as a kid.

I think grout can be stained if it's not sealed yet (ask your tiler). in that case, I imagine it can be put on in wide strokes and wiped off the tile.

or if it is sealed, there are products like "grout renew". I wouldn't recommend it for a shower or any area that needs to be cleaned often. it's basically paint and will eventually chip off with regular cleanings. for a brand new shower, I would not want to add that level of maintenance.

I usually pick grout using the plastic sample sticks. I find one that matches my tile and then order a darker color! Grout always ends up lighter than the sample. Better yet, also use the epoxy grouts that come premixed and it eliminates the human factor for mixing up grout and messing it up with too much or too little water.