The super fancy restaurants receive an evil eye 

from me if they never respond. Is not responding really worth all the headaches that develop as a result?? 
I keep a running list of restaurants that are inflexible and not accommodating without having a good reason to not accomodate, when I have asked for accomodation. I don’t visit the same restaurants when I don’t need accommodating and/or a 2 top for 2.
A restaurant that is willing to save an empty table of 2 for 2 customers who might show up, while turning down a table of 1, who is ready to sit down and order, is intolerant towards solo diners, and this adds to the stigma people who are alone face.
I realize many solo diners eating alone are asking for a table of 1 because they’re on business or want to eat alone.
For a restaurant to say they only allow tables for 2, that sends a message to people who don’t have a second person to fill that spot at the table.
I have travelled quite a bit as a solo traveller. I haven’t run into poor treatment at too many places.
The only places where I can remember being treated poorly because I was alone, was at a Westin and at its restaurant in Kauai, by a taxi driver in Kauai, by a tour bus driver/tour guide in Oahu, and at a luau on Oahu.
Every other restaurant I visited in Kauai and Oahu treated me well.
Those were isolated incidents. That Westin was charging $450/ night in 2019. I was paying the same amount as a couple or a family with 2 kids would have been paying for the room, yet I was being treated like I was unwelcome.
The hotel restaurant seated the 4 single people so they were facing a fake stone waterfall, all in the same direction. 
It was very clear that the 5 or 6 unwelcoming people I dealt with on Oahu and Kauai were geared towards buttering up couples and families. They didn’t think about the fact that single people or solo travellers are also paying good money for their vacations.