> they are approximately the same absolute price today that they were 30-40 years ago, without adjusting for inflation.

You used to get a lot of stuff in a game box that wasn't just the game though. Manuals were often very detailed, arguably works of art in their own right. Also the cost of producing and shipping games is way lower online than it was for physical copies. Companies all used to have to develop their own engines and tooling to build games, that cost is mostly just gone with Unity and Unreal now.

Last and definitely not least, there's way more competition in the gaming industry now, and that tends to drive prices down.