I think most will be reasonable about Covid, or if you are a regular customer with a track record of reliability. People cancelling because a friend has asked them to go for lunch, or because it's raining, however, is a different matter. Would people want their salaries or pensions to be subject to the vagaries of other people's whims in this way?
I read that people were booking several tables in different restaurants then deciding on the night which one to go to. The others lost the income, and may have ordered ingredients in expectation of a group, too. When restaurants started demanding a deposit to book, they were outraged.
On this thread we may all be reasonable people who stick to our obligations, but there are a lot of others who think that 'self care' means that they should feel no guilt about letting others down if they don't fancy doing something at the last minute - the other people should 'be kind' and understand 🙄. I have little patience with that viewpoint when it is people cancelling a date for coffee, but when it is someone's living I don't blame them for expecting compensation.