Impractical Online Reservation Restrictions

The online reservation is extremely frustrating. How many people can make a booking 24 hours in advance for a take away or even a sit in meal? Twice now I've wanted to use a Groupon and the restaurant had plenty availability but could not go because the reservation website does not allow bookings within 24 hours. Also, these rules are not being explained to the restaurant owners and manager as they were unaware of this. More importantly when one purchases a Groupon it is not mentioned either.