The salary issue (along with the working conditions) are because game dev is an "art" field which meant, like other creative jobs, companies can life in young, naive people and exploit their passion to get them to accept terrible conditions because "wow I get to make a game". I suspect this is why triple A games are so terrible nowadays, most of the talented people realised that corporate game devs suck and going indie is the best path. Web design is also creative obviously but mostly going to consist of making corporate pages, not something most people can be passionate about.