Why are fonts more expensive when used in games?

I'm a video game developer who loves fonts. I noticed that fonts are often more expensive when they are bought to be used in games.

For example, a font called Daft Brush on HypeForType is sold for $20 when it is for "desktop" usage is, but is sold for $400 when bought to be used in games.

Is there a specific reason for that?

Thanks for your help.