There actually can be bs from a manufacturer where a site cannot list an item below their MSRP so in order to do a sale they have to do the bs like "add to cart to see price" or making you sign in. Sure sometimes it's not an amazing deal but it can often be the lowest price you can find an item because they aren't allowed to advertise a price that low.

Edit: See comment below to learn about MAP "minimum advertised price" which is different from MSRP "manufacturer suggested retail price" leaving my above comment alone with its inaccuracy so that the below comment continues to make sense and you can learn as I did.

You're being too generous...

It's usually the exact same price or higher.

Costco online is the only exception to this, for me. You need a paid account to shop there anyway, so I'm willing to jump through that hoop most of the time. It's still a pain, and I've definitely closed the tab a few times on Costco when I was pretty sure I was getting a better deal somewhere else.

Thankfully not too many, Often I'll find some things are marked but not everything in smaller stores like some grocery, variety stores, second hand shops etc.