I don't think they are trying to get revenge. They are trying to cover for their own failings. By any reasonable means, the vaccine rollout in continental Europe in relation to the wealth and logistics available compared to US/UK is a complete failure.
Goals and announcements have already been missed, and it turning out to be unnecessary can be muddied, or buried.
Assuming this is indeed politics, there are a lot of positives to this type of move in an already shit situation.
Except, you know, order enough vaccines for their population. Other than that though, everything that they can!
And yes, governments are doing everything they can. And the screw up with vaccinations. No idea why, because I don't have all the details, but maybe AZ is just coming in time to have been 1) a good scape goat early on when one was needed during the frustration with vaccine deliveries 2) bad at PR 3) earned a bad rep and now everybody is over cautious. And public / media pressure isn't really helping.