I think the difference is in the scaling: cooking doesn't scale vs income in the same way that eating out does. So in the absence of enjoying the act of cooking

I think the difference is in the scaling: cooking doesn't scale vs income in the same way that eating out does. So in the absence of enjoying the act of cooking (which I happen to) there is absolutely an hourly rate threshold past which it makes no financial sense to cook. If I save approximately the same amount cooking vs eating out, but it takes me the same additional amount of time to cook (again, assuming you don't enjoy that), then as my income grows the smaller the savings become as a percentage and the larger the monetary value of a given amount of my time becomes worth.