>When an affordable architect specs a house, they almost never spec a shower valve (let alone cabinets, specific flooring providers, etc). When you buy a shower fixture, the valve doesn't come with it. This means you or the contractor has to either drive to home depot to buy a 6 dollar valve, or install the wrong valve to pass inspection and then wait and reinstall the correct valve.

This is kind of an eyebrow raising statement.

You definitely can buy a shower fixture with a valve.

They're not $6. Cheapest is like $40 retail and they can be hundreds for fancier models.

Nobody is installing a valve and then reworking it after passing inspection. It's pointless and will cost hundreds in wasted material and labor.

If your desired trim kit is out of stock you're only going to find out after the wall is waterproofed & tiled. Nobody is ripping out thousands of dollars of work to change a valve. You'd just buy a different trim kit that matches the installed valve.

I dunno, maybe they do things differently in California. But what you said there doesn't match any sort of construction experience I've had.