We largely have these regulations in the US too (at the state level), we just don't reuse them. Naturally there are rules about what is livable versus what is not. A balcony is not. A room with no windows isn't even a bedroom. That kind of stuff.

It would be truly trivial to then just transform that to calculating square footage, and many states do just that. But not all. It's a problem of motivation, not necessarily ability or cost.