In the single and multiplayer screen some buttons are not highlighted as a button but text informations are hightlighted. That looks very strange and confusing newbies and me.

local/UTC: Is simple text. Why they have a button background?

At the other side "Driver", "Garage" and "Track" are not highlighted like a button.

I don't think it is a problem - for me.
The Local/UTC fields have a grey background so we can see them better, I think.
And the Driver, Garage and Track buttons are buttons, just you can't see them highlighted because of the dark background. (See my attached picture, I changed the background to a plain white one.)

> just you can't see them highlighted because of the dark background
Hm, ok - thanks for the hint


But with the default background image the buttons should be better visible then now. A lighter gray for this buttons can help.

You can actually adjust many menu colours in the game. Go to Options > Display and then in the bottom right corner there is a big "Interface" button. It takes you to sliders to adjust many menu colours, the one you are searching for is the "Big Button".