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,

1. 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).

2. 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.