There is another way. It involves no money and nothing for the restaurant to do. First come first serve. Basically you want in. Show up and stand in line.
I agree for places like doctors visit though. Everyone should stand in queue rather than a limited reservation.
What if my work schedule isn't flexible? Having a queue and no option for an appointment time means that I'll essentially never be able to guarantee a doctor's visit. I'll just have to schedule time off and pray that the line isn't too long.