Why are European revolutions usually called incomplete?

In the middle of the 19th century, a revolutionary wave took place in Europe. The revolution took place in Germany, France, Italy, Austria. However, these revolutions did not have the desired effect. In this connection, soon in these countries there were even more significant political and social shifts. This is how the revolution took place in France in 1871. In Italy, the war with Austria continued, which ended with the unification of the first. Prussia became the central German state, which was able to unite other German lands around itself.