You're describing content, not form. Many websites also have to show the same things (login button => speedometer) but they don't have to look the same.

It struck me recently that most cars are increasingly looking the same. It used to be that Peugeots had a very typical nose, Volkswagens had their own boring but efficient look, Volvos were kinda blocky. These days I can barely tell the make of a car by looking at the lines, and that's because they all need to perform the same function: transport a similar number of people at similar speed with as low fuel consumption as possible. So they all have basically the same streamlined lines.

Most websites want their navigation to be found, so they put it in the same place as every other website. They want their story easily readable in the center.

There's still plenty of variation, but sites with similar goals are going to end up with a lot of similar elements.

What exactly is the benefit to making things different other than satisfying some designer's need to be "creative"? It's helpful if you can expect login buttons to be in roughly the same place every time, navigation elements to be arranged the same way and point to the same types of places - Home/Products/Support/About/Jobs.

Being different for the sake of being different just wastes people's time trying to find stuff that isn't where they expect it to be.

Lack of innovation means lack of improvement. Endevoring to do things other than the rote way can lead to a better way.

You don't drive a Renault, do you.