mode share even in tokyo is only 51% - they have a lot of work they can do. That 51% is likely just going to work, cities rarely collect data for other trips but those matter and are places to work on.
i mean none of the supermarkets close to my home have parkings... (they have a bunch of bike racks though).
there is 1 combini with a small ~6 spots parking that sits mostly empty. my building has more units than parking spots, there are a lot of bikes though.
in tokyo, having a car is not the default, you need a good reason.
now if you get out of tokyo (like gunma), it's another story, in japan they talk about "car society" (kuruma shakai). you'll see lots of cars, and big parkings.
That's probably why they have so much ridership.