When you call a floor refinishing contractor, they quote you for refinishing. That is the only service they sell.
Refinishing means sanding the floor down to bare wood and starting over from scratch. New resin. New finish. New everything.
It costs $7,000 to $9,000 because it is a complete rebuild. Three weeks of disruption. Fumes. Moving furniture. Starting from zero.
But here is the thing nobody tells you before they hand you that quote: most floors with white scratches and dullness do not need to be rebuilt.
The wood underneath is almost certainly fine. The problem is in the finish on top of the wood, not the wood itself.
And a finish problem is not a refinishing problem. It is a maintenance problem. Those are not the same thing, and the difference in cost is about $8,700.