Without having done any actual surveys, I suspect the number one reason OpenTable works is because a lot of restaurants are absolutely lousy with online reservations.
You can e-mail them using their online form or provided e-mail, and any number of these can happen:
- You never get a response.
- You are lucky to get a response days later.
- You get a voicemail asking you to call them.
- WTF? I E-MAILED you because I wanted to handle this ONLINE. Why do you bother having an e-mail address?
- An answering machine and phone tag.
- It's so noisy over there they can't hear you anyway.
- A conversation that could have taken a fraction of the time had you done it online.
TIP: If the restaurant you are looking for is not on OpenTable, they might be on the similar service BookEnda.