I can see where you're coming from - but I totally disagree. It is just good planning IMO, to get the table prior to the food just to avoid that very result - no where to eat. No way am I paying that much money for chicken nuggets only to end up not being able to rest my legs (and have my kids take a much-needed rest) and relax while I eat them. I put a lot of thought/planning into mealtimes just to avoid that situation and getting the table prior to the food (even if it means - depending on the crowd - waiting for awhile to ge the table I want) is key to that plan. When I go alone with my kids I intentionally choose places where there are tables close enough to the food lines that I can have them sit there and have my eyes on them the whole time (and they can hear me if I need to remind/instruct them on anything). And then I wait my turn for these tables (just like everyone waits during busy times, I just choose to wait PRIOR TO getting my food - like I said, I just consider it good planning). So, I, too, wait for tables - I just choose to do it first instead of after - so we're in the same waiting boat - you just choose to do it after the food is in hand. It is up to everyone to choose what works best for their tour plan - mine involves showing up early to the restaurant, staking out and waiting for my table THEN getting my food. So just because I choose to spend that extra time doesn't make me rude.
To me this is analogous to saying that people that stake out the best parade seats EARLY are being rude to the people who show up and all the seats are gone. They choose to take extra time to stake out where they choose to sit - politely wait there until the parade starts - they are ENTITLED to these seats. Just like people who wait patiently for a seat at a restaurant are entitled to these seats, IMO.