Great point. "Yes, I know you had a reservation, but we sold your table to someone else. I can't do anything here, but if you call the 800 number a robot will send you a $20 voucher for your next meal."

The funny(?) part is that a lot of customers won't mind if they got a meal voucher for the future. When they don't mind it for air travel they will surely mind it even less for food where there are a ton of other options available.

Could restaurants be successful by giving free food (vouchers) to people who make reservations but have no peference for the restaurant, i.e. are happy to go elsewhere? Sounds like Groupon, another bright idea pitched to small restaurants.

I'd say it's closer to priceline.

I could see it go either way - I'd expect people to hate it more, actually. How fun would "oh hey, we don't have anywhere to get dinner, but we have a voucher" be on a date? Especially a first date?

Might be a positive on a first date, it would add some adventure to it and also increases the chances of a second date as you have to use the voucher.

That actually happens and I don't feel it's wrong. For example:

The pre-theater menu, which offers a discount if you eat and leave before a specific time. I could also imagine that tables booked for a less desirable time window are sold cheaper than when you want it on Saturday, 8pm.

Airline yield mangement gets a lot a flack, but I really don't get what's inherently wrong with the process.

Yield management is a form of constrained optimization, and it's tempting sometimes to relax the customer experience constraints to favor a higher (short-term) yield, as we see from time to time with the airlines.