It is frustrating, isn't it? There are probably two main answers:
1. It's a "cosmetic" issue.
Many people don't think it's a big deal, so there's not much research or regulation.
2. It's much, much harder than you'd think.
Until I started doing all this research, I thought the same thing. The problem is that hairs are surrounded by nerves, so anything strong enough to pull them out or destroy them with energy or chemicals is going to affect the surrounding nerves.
Check out the shot below to see what I mean:Hairfacts: hair follicle nerve photo
In fact, a sure-fire way to tell a hair removal product is a scam is if they use the term "painless and permanent."
Destroying hairs while sparing surrounding tissues is very difficult, just like destroying cancer cells. In fact, there are a lot of simiarities, which helps explain the difficulty in curing cancer. Also like cancer, hair growth is affected by a LOT of things, so it's very hard to deal with all of them.
In the meantime, there are several imperfect methods. It is possible to remove hair permanently, but it will take some doing.
I suspect someday, they'll figure it out, but until then, I think this site will have plenty of visitors!