Does any manufacturer do king beds right?

I feel your concern.. when we purchased our used keystone challenger, it had a king mattress installed but the plywood support underneath was only the size of a queen mattress! The lady who owned it previously used it like that for years... took me a while to figure out why I was rolling out of bed if I neared the edge! Lol.
I quickly installed a proper sized base for the king mattress to this day I still can’t believe they built it like that... oh wait- yes I can.