That doesnt look like cracking caulk. It looks like very sloppy, awful caulk application. Contractor needs to come back and thoroughly clean caulk out and run a proper bead of caulk in those joints (neat and smooth!) If getting that person back isn‘t possible, you can do this yourself after wacthing youtube videos; if you’re a perfectionist that trait will help. But for a new bathroom this a crying shame.

Weathy, thank you. I’ve had the same thought but was willing to accept function over form. But it seems perhaps bad form is also leading to bad function. The contractor has been very friendly and I fear that as a result we’ve just been too lax regarding workmanship. The job also took much longer than expected due to some (previously unknown) quirks of our house, and at a certain point we just wanted it done. But you’re right. Ugh. Now the question is whether to ask him to fix it or pay someone else to do it.

A related question: is it okay to keep using the shower while it’s like this or do we need to use another bathroom until it can get repaired?

As long as the caulk is sealing the joints you should be okay.

The main issue for the OP: How was the waterproofing under the tile done? Although you need to get that caulking removed and redone, having cracked grout or cracked caulking doesn't matter from a functional standpoint if the waterproofing was done properly. Was cement board used for a tiling surface? And were the joints taped and a proper liquid membrane applied? I ask because sloppy work, like that unworkmanlike caulking, is often a sign of someone who cuts corners or is otherwise incompetent. Grout cracking where the wall-floor seam is could be a sign of movement of the shower pan or the effects of water getting through to the materials under the tile due to inadequate waterproofing. Cracking of the grout on the walls could be a sign of movement underneath the tiles or water intrusion, too. I'm not trying to be alarmist, but it would be good to know what was done to prep the shower before the tile was applied.

I agree. All to often, either standard "latex" caulk is used or what is referred to as "Siliconized Latex Caulk." No, No, No! ONLY use pure silicone caulk! Best resource for a perfect color matching silicone (sanded or unsanded) is www.colorriteinc.com Available online and give them the grout company, grout name and/or number and they can accommodate you....

Joseph, The Pro, if applied properly, how long should silicone caulk last between a tiled wall and a cast iron tub in a family bathroom?

Done properly....years.

^ Yes.

I meant how many years? 3, 5, 7, 10? Does silicone last longer than latex? I had zero luck getting a smooth and tidy finish with silicone. (Is there such a thing as a bad tube? Cleaning that silicone out was a big bear). After that attempt, I used latex and it looked great, sealed perfectly and lasted about 7 years. Been using it ever since in our home. Should I be using silicone because it lasts longer? Just wanted to understand the silicone advisory. (Sorry, OP, about veering a bit off topic in your thread).

Latex is easy to use...cleans up with water and doesn't last long. Pure silicone wants a deep and dry joint and should be good for ten years or more. Tooling it is a bit more complex and the remainder needs to be cleaned up with some alcohol pretty quickly as it skins over fast. A good practice is to use painter's tape on the borders and remove it quickly. There are plenty of YouTube videos on technique.....

Avanti, thanks for elaborating.