It's morning and don't have a lot of time but this is an interesting question I wanted to answer while it was relevant.
A lot of people have touched on the basics which kinda follow along any industry. Price gouging, variety is more expensive than just making one repetitive design, etc. Few things I wanted to touch on,
-
You shouldn't really be replacing faucets that much. They design them to have internal structures which can be replaced. Even the crappiest low cost items can be fixed with a few bucks (they call these mobile home models, what gets put into all the mass manufactured items and are usually in a different section all to themselves). Pick a design you want and look into it's replacement parts to save some money (if you're worried about the part being reliably available, just get like 3 kits and you'll be set for life).
-
Supply chain cost. Manufacturers make a product for 30, they sell it to distributors who mark it up to 50, they sell it to a store who then marks it up to 80. Home Renovision DIY has a great video detailing the process, compares online vs boxstore vs plumbing store. Also cuts them open and shows you the internals which is all great with a 13min video.