But it's not a problem for the places taking the reservations. They're thrilled whenever they manage to book solid. It's only a problem for the non technically minded people looking for reservations.
Are all the bot reservations actually made with the intention of a human going to the restaurant? I wouldn't be surprised if some people used these bots just to prevent anyone else from making online reservations and screw with the restaurant/customers.
Based on the bot's code [1], it looks like all they ask for is a phone number and an email address. It might be a good idea to at least require a captcha, if not a credit card deposit of a few bucks.