The way this article is worded makes it sound like Denmark has a 'book tax'. Denmark has a VAT on goods (and services), which is 25%. But Denmark doesn't have split VAT values, so it's either 25% or nothing; no in-between. So they are just proposing removing the VAT from books. (Some goods and services are already exempt from VAT.) And if you wonder why Denmark doesn't simply lower their VAT or introduce a split VAT…
Insane that technical debt and general incompetency in software can produce such unexpected side effects.
Ad the other commenter wrote: The 25% is assumed - this has nothing to do with competence but to what level an assumption is true.
Everybody can point fingers at 25 year old code and call the developers incompetent because surrounding requirements have changed.