Its not enough that you change the fine print in a 20 page long legal contract. A restaurant could easy require you to agree to an customer agreement on the point of booking a table. It would still not allow them to book 50 people and make food for 10, arguing that their capacity to make food is full. Even if the customer agreement said that the restaurant is only responsible to supply food "up to" all-you-can-eat. The police would classify such scheme as a scam.
> It would still not allow them to book 50 people and make food for 10,
Is something like a 5 to 1 over booking happening with google fiber? Overbooking is common practice with airlines and many business that have solid statistics that tell them how safe it is to overbook. It is not normally considered, when done in a reasonable manner, a scam to do so either.