Under its current name, yes, but the European Union we know today is really the successor to the European Communities of yesteryear.

> Since 1975 there is a currency (and monetary policy),

Which the UK doesn't participate in, mostly.

> there is a proper and separate legal system,

This isn't new. There has been EU law since before the UK joined. The European Communities Act 1972 specifically provides for the conversion of EU law into UK law, and its supremacy over UK law.

> there a real political process with a parliament and an executive and many other changes.

The European Parliament existed long before the UK joined, and has been named that since 1962. But in fairness, it only started having elections in 1979 (it was previously appointed).

The European Commission, the executive, also existed before the UK joined. It has been a single body since 1967 (and there were three executives before that - their merger is sometimes considered the beginning of the modern EU).

> Trade is now only a part of a much bigger story.

It's always been part of a bigger story. The European Economic Community, after all, was only one of the three European Communities we joined.

> In 1975 there wasn't even a flag - the circle of yellow stars was a symbol used by different pan-national organisation (that still exists) with no relation at all to the EEC.

So? Lots of international organisations have flags. The Commonwealth of Nations has its own flag, and it's never considered a superstate.