I would say that anything more than the basic takeout/fast food and the like for when someone can't cook/make shabbos is a luxury.
Simply-a luxury restaurant is exactly that-a luxury.
I understand the point in their existence and do not mean to say that going to one make one a baal taava, but to make it a chov kadosh is ridiculous.
Question: If the aforementioned restaurants were 1000% kashrus compliant but unprofitable and about to close would you consider giving maaser money to the owner "for the sake of kashrus" to help him stay open so that there should be more restaurant options available.