In case of Nobu, I went there for lunch, and there were several free tables at that time. I felt unwanted anyway and it spoiled all my pleasure.

Well, I am going to have a solo lunch at Nobu and booked a table for 2 on OT (no option to book for a party of one), and they told me by phone what they "would allow me to have lunch but for my future consideration they request a minimum party of 2"