Not just the Netherlands, most of Europe counts floors like this: ground, first, second, etc.
I think it wildly differs all around Europe.
In Spain for example, if someone says "1st floor" it can be two or three floors above the actual ground floor, if there is a "Entresuelo" or "Principal", and you start counting after those. Actual ground floor is "bajo".
On the other hand you have the "atico" (attic) which is the top level floor, unless there is a "sobre atico" ("above the attic"), so just because you live in the attic doesn't mean you live on the top floor.
Then every region can have their own convention, or even difference in neighborhoods in the same city.
Call it the Ugly European effect. https://blog.codinghorror.com/the-ugly-american-programmer/