Exactly what a high end place I went to in London did. Seemed fair enough. Places are in demand but I’m not being screwed in to paying for the privilege of being able to pay, but at the cost of locked in to committing or lose £50 to cancel on short notice. I’d be fine with this being more normal.

Almost every high level, Michelin type restaurant does this

The pricing is not dynamic though, at any Michelin restaurant I've been to. Even if it were, I'm not sure there would be any change though if the consumer knows that their net cost would remain the same, so it doesn't really matter how much the restaurant charges for the reservation fee.

This is the segment where I least understand the lack of surge pricing. Noma closed because "it wasn't sustainable". Meanwhile people made reservations as soon as they opened up and traveled there from across the globe. I know I'd paid more than they charged and I'm no billionaire.

I guess the people who works there don't just want to make food for the super rich. Maybe they have friends and family, and they want to imagine that the experience they create would also be available to people like that. And if that's the case then the "low" price is a fundamental requirement, and it makes sense to say that it's not sustainable (the combination of the quality and the price).

As I said in another comment, El Buli solved this decades ago by setting a chunk of reservations aside for locals from the town they were located in and another chunk only for people from Spain. Just do that and add a portion for friends and family.

I used to do consulting for a extremely high-end hotel where a single night could easily cost $3k+. Every employee got to spend a night for free every year and they got a number of friends and family discounts that were 90% off.

And the popular ones still sell out immediately because the prepayment doesn't change that they are charging below the equilibrium price.

If you want to eat Le Tour d'Argent in Paris, the world's oldest restaurant, you have to pay $500 per person in advance just to make a reservation.

This is really common now for online reservations where I am in the UK. If you phone up, you won't be asked for a deposit. I assumed it was to combat bots. My favourite restaurant was charging £20 a person, refundable against the bill. It's a £30-40 per person restaurant.