There's a very good reason for that. If you take reservations for tables that are obviously better than the others in a restaurant - outside in nice weather, great view etc - then every single customer will ask to be sat in them and be disappointed when told that they are already booked so you have already pissed people off a bit before you have even started.
Even worse, if a customer turns up at 12:30 for example and asks to sit on a prime table and is told that it is booked and then the person who it is booked for is late or doesn't turn up at all, a customer can spend the whole meal looking at the empty table that they were not allowed to sit at and end up seething and vowing never to return.
Far better just to seat the prime tables as people arrive and then later customers can see that the tables are full and can either wait for the next one or sit straight down
Nope - that's fair enough, I hadn't really thought of it like that. It's a bit frustrating though - Mrs W and myself are lunching this Sunday and want to sit outside. Tried to book R&F but as we couldn't guarantee to sit outside we've decided to go elsewhere. I have no doubt they will fill all the tables on Sunday regardless though.