for the .ro (Romania) domains this is not really true. the national domain registrar (rotld.ro) doesn't charge anything for updating name servers. probably the additional fees you're talking about are imposed by some third-party / reseller.

what I also found interesting or at least peculiar is that the Romanian registrar charges a one-time only fee for registering a domain and it has been doing so for as long as I know. you pay 50 Euros per domain but you get to keep it for your whole life or as long as they don't decide to charge on a yearly basis. I'm curious if there's any other domain provider offering lifetime registration?

.dk danish domains is free. Where do you get that price from?

Could you please provide the source of this information? As far as I know it is not true at least for .cz domains.