That's just because you don't understand what "socialism" means. Maybe you meant communism? It would still be debatable, but not completely wrong.
For instance, saying that public transportation should be public (i.e. belong to the state) does not mean that the state is authoritarian. You can have more moderate forms of socialism.
I find it interesting that the Wikipedia articles are pretty different in different languages. In French it is much more moderate than in English, for instance: https://fr.wikipedia.org/wiki/Socialisme.
Sure, but that's not socialism. That's state capitalism at most.
There is not gradient. If society is socialist then as per definition and as explained there must be authoritarianism to suppress any private initiative.
The article in French says the same thing as I wrote before: "socialist parties" are no longer socialist:
"Le socialisme démocratique, c'est-à-dire un socialisme converti à la démocratie libérale et respectueux du jeu parlementaire, représente aujourd'hui la tendance majoritaire des partis socialistes, qui n'envisagent plus la rupture avec l'économie de marché."
If they no longer want to get rid of the market economy and private ownership then they are no longer socialist at all! Socialism has demonstrably failed so they have been trying to adapt while keeping the name...
This logic works both ways. There is authoritarianism to enforce private ownership in capitalism. The police is a tool of the capitalist class, designed to suppress any protest against the capitalist system. It even extends internationally, to Imperialism. One only needs to think of banana republics, or more recently, Coca Cola murdering union leaders.
That's not what the sentence you quoted says. Do you speak french? Just to know (respectfully) if we need to debate the meaning of that sentence, or if I need to translate it for you.
That sentence precisely means that there is a gradient.
You think that it's not socialism anymore (which is fair, "socialisme democratique" is not "socialism" anymore), and I say that socialism has evolved ("socialisme democratique" is an evolution of socialism that works in democracies). In the end it's just a difference in the definition.
The fact remains that the US don't really have the equivalent of "Parti Socialiste": the democrats would be on the right wing in France, right?
These days there is a tendency to use socialism and practical present-day social democracy rather interchangeably, but I think that is problematic (and the latter doesn't really aim for socialism anymore, I'd say).