I think people would find ways to partially skirt the law using formulas.

There are some legitimate uses for formula pricing, e.g., rent a U-Haul with a per-mile cost, or a cell phone bill with a per GB data cost, or a per-user SAAS model.

I imagine a dark pattern for the "resort fee" might be a complicated formula described in words in size 6 font at the bottom of the page if you took the time to read the footnote.