Most modern apps use standard logging libraries rather than writing their own bespoke logging modules for their code. So if the router software is written in a language called lua they may use the log4lua library. The point is these libraries are configurable so you can turn logging off, have minimum logging or maximum detail. The logs are useful if there are problems and you have some indication of what when wrong. Very few people sit looking at logs so if you don't want to see anything you can turn it off on the 192.168.1.1 router page
It isn't Vodafone spamming, its the actual code on the router being executed at the time thats writing the messages and telling you what is happening, you can turn logging off. Logging has a small overhead so turning it off makes it ever so slightly faster
