I bought a new wallet lately.

It's a leather bifold with a pouch for paper bills and a slot for 1-2 cards. Since it doesn't have tons of card flaps it's super slim, which is what I wanted.

My old wallet was "slim" with a bunch of internal card slots (in a stadium seating arrangement) which was way bulkier. It also didn't have room for bills laid out so I had to fold them in half and take out the whole bundle to make currency payments. Now I can thumb through the bills like pages and pick exactly what's needed.

My impression is that most people these days (in a big city) use cards or digital payments and not cash.

If I were manufacturing wallets they would be one big card pouch (holding maybe 5 cards) either singly or as part of a bifold for paper notes.