"My readers in Europe, can you shed more light on things?"

1. The sentiment of the population changed drastically in the last months. While initially there was a lot of fear, concern, seriousness, and responsibility, it got replaced by fatigue, sloppyness, conspiracy theories, and hopeful thinking. Put simply, the "Covid isn't that bad, just a little worse than the flu maybe. Also masks don't really work! Muh freedom!"-faction increased in numbers.
2. The strategic management and policy response from governments changed drastically: While initially it was "better safe than sorry" it became "doing the absolute minimum that is required, and keep the measures as soft as somehow possible". The numbers in summer sank to an all time low, and policy makers where resting on them, while not taking precaution and prevention measures for autumn. Schools opened (almost) normally in many countries, work continued normally, people started to gather more and the regulation on events and gatherings got loosened up a lot too. There have been no regional quarantines, making covid spread across borders easily too. Even as cases jumped rapidly, measure adjustements were very mild. If you want to check one of these "curious examples" check out Czechia or Austria in particular. In Austria work and school still operates at full level, no teleworking regulation.
   
   As an Austrian citizen, I'm absolutely not surprised at current developments and am deeply dissapointed on the horrible progression for both citizens, as well as policy makers.

Also, the graph you posted from twitter is to be taken with a lot of caution:

1. No relative numbers (cases per X citizens)
2. No adjustment for amount of tests. To account for that, one could work with "% of tests positive", but even that metric is tainted as it doesn't adjust for different "testing strategies". For example, one country might not even test close-contacts of a positive case, and just put them in quarantine, and the other does. It will result in different "% of test positive" numbers.