My wife and I had to sit at 2 different tables at a Japanese restaurant yesterday. These are the rules set not by the restaurant, but the local governing body. I find your harsh behaviour toward the restaurant unfair. We had a nice meal under the circumstances and did not complain. How should the restaurant know who lives together and who can safely eat together. Another thing you should consider is that when people eat at a restaurant, they take off their masks, so the distance becomes more important when people are not wearing masks.
If you see some restaurants not enforcing the same restrictions, then those restaurants are disregarding the rules currently in place for restaurant dining. In the Mall, EVERY restaurant I saw had such restrictions. In restaurants which allow more than one person to sit at a table, they have screens separating diners.
You are punishing the restaurant for restrictions that are not their doing and certainly not their choice. Why not help them out? It upsets them more than it upsets you. Maybe you can find a restaurant where the seats are low and you can still chat to your friends/family who are sitting at different tables.