They are so unwieldy that the US has a passport card because the passport is too big for frequent travellers. I also will complain about how my passport's ID page is the second, not the first page, so you open the passport, and then always have to flip to the second page (unless you use a tiny bit of tape).

The passport card is almost exclusively for people who go back and forth to Canada and want to keep it in their wallet. Nobody is complaining about the size of a passport.

The passport card is only used for land and sea entries, it's not a full replacement for the passport (would be nice if it was) and never has been. It does work as a federally issued ID if you need one.

What. No. A passport card is not the same as a passport book in its capabilities.