> the communist bloc happened on a backdrop of happy workers

Were workers happy in those countries? Likely no. Was it their populations that chose Communism? No. It was mainly imposed upon countries by Russian imperialism. The cold war was a power struggle, not a struggle between different peoples who chose different ideologies. You can see that in how quickly the Warsaw pact disintegrated after the Soviet Union lost their grasp on those countries, and in how much many of the ex-SU / Warsaw Pact peoples now hate Russia, except for the countries that were taken over by authoritarians.

> Were workers happy in those countries? Likely no.

But that's not the point. :)

Was there solidarity among workers internationally? Yes. Because they're in the same class in society.

There were many attempted communist revolutions around Europe in the late 19th century and the early 20th century. In most cases, large parts of the working class had decided that their own country was the enemy that had to be destroyed. They had no loyalty to the state, but they found natural allies in revolutionary communists in other countries.

You are talking about much later events.

Emphasis on attempted. We also had a wave of red terrorism around the world in the 70s, which led to nothing but grief. Ultimately, what improved workers' rights in the West was a democratic process. In Latin American countries you get governments swinging from populists on the left and on the right constantly. But either way, I don't see any communist revolution coming about anytime soon, even in very undeveloped countries, many of which already lived under some sort of communist dictatorship in the past, or at least live close enough to one to know it didn't do any good.

Democratic process had little to do with it.

Many of those attempted revolutions turned into civil wars. Communists won some of them. Some of the emerging communist states were defeated by foreign military interventions. It was a bloody and confusing era in European history.

The turning point was when capitalists realized that it was not possible to defeat communism by fighting the communists. They gave in and started supporting some of the goals of social democrats and moderate socialists. That deradicalized enough people that even revolutionary communists had to start working within the system.

Revolutions are pretty common around the world. The recent ones have not been motivated by communism or anything similar, but that could change. The world is unpredictable, and major changes happen once in a while.