Teletext have more than a million users in Denmark. Truly surprising to me but it is also kinda awesome. It certainly still serves a purpose. No ads, no noise just pure signal.
On the site [1] of the NOS (dutch broadcast foundation) there is even a big button in the header. Clicking trough the news items on the site is very slow compared to clicking trough news items on the Teletekst app.
The TV stations not broadcasting from Denmark, and not funded (at least partially) by public money had similar ads. Either for adult services, or betting.
What most view as "the real teletext" is the service provided by DR (Danmarks Radio), the Danish equivalent of the BBC. They are not allowed to show ads anywhere.
[1] https://nos.nl