DNS records, e.g. zone files, are supposed to be public information.
As such, ICANN requires gTLD registries to provide users with access to them.[FN1]
However, various ccTLDs at various times refused to comply, and most still try to pretend their zone files are private.
Obviously, as the blog post shows, users can still get a large quantity of the data freely from other sources.
Google search results for ccTLD zone files are dominated by individuals who have done so and are selling this data. IMO, this sale of public data is unnecessary, not to mention annoying.
Last year .se and .nu started making their zone files public.
https://www.iis.se/english/press/pressreleases/iis-releases-...
They were also the first to try their hand at DNSSEC. As the blog post shows, DNSSEC makes it easier to get contents of a zone.
FN1. "About Zone File Access
Registry operators must provide to ICANN bulk access to the zone files of the Generic Top Level Domain (gTLD) at least on a daily basis. For gTLDs, a zone file contains information about domain names that are active in that gTLD. In general, Internet users may be able to access and download zone file data at no cost for certain purposes.
This contractual obligation does not apply to any ccTLD (such as .us, .de, or .uk). If you have a complaint about gTLD zone file access, please submit a Zone File Access Complaint Form."
source: https://www.icann.org/resources/pages/zfa-2013-06-28-en