Carrefour stocking is typically like that anyway - the cans run low over a couple of months, and then one day they’re restocked.
Not sure where you are in Taiwan, but Trinity Indian has plenty of lentils and other legumes, usually cheaper than Jason’s I believe. You can often find different beans at local markets as well. I think the high prices are because that sort of stuff is pretty much only bought by the narrow organic / health market here, but I’ve wondered about the prices as well. Most of that, I actually order from iHerb.