>But you don't have the same party ruling in U.S. for several decades It depends on what country you're talking about, but looking at which party is the bigges

>But you don't have the same party ruling in U.S. for several decades It depends on what country you're talking about, but looking at which party is the biggest/who the prime minister is and summing it up as the "ruling party" is a gross oversimplification of the power dynamics in a parliamentary democracy. The power balance shifting between smaller parties can bring about huge effects on the government and the policies that are passed.