Again, you still aren't following. I'm saying many sites don't do that. You are correct, I should be able to see estimated shipping from my cart on any e-commerce site by just putting in a zip code in, and them knowing what is in my cart (product wise). It's a dark pattern that MANY sites don't do this, they make you fill out a ton of info to get to that point. It's sketchy and a dark pattern to put that many walls behind a final price including shipping. I understand there has to be a few walls, but you wouldn't believe how many sites put extra walls in there to try to "trap" you in their funnel.
Where you see dark pattern is in fact a limitation of most ecommerce platforms. Shopify, which powers millions of retailers website, doesn't offer this out of the box. You need the advanced plan ($$) and on top of that you need a special app/theme that would allow you to do it before checkout.
