From real life observations, TotallyLovely.
Only invite nice kids - usually my definition of nice is not the same as DD's. So I can't really say, you're not inviting X, they aren't nice.
Put on the invite no siblings - leading to "well I can't bring just one"
Vile parents - you can't say Piss Off.
Map - doesn't work for lots of people.
To Be Picked up at: doesn't seem to work either
Veggie alternative - this bothers me less than all the others. I could do this easily, having friends who are vegetaraian, vegan, lactose intolerant etc. As long as I know.
Epipen - happened in a Pizza Hut party I went to. Mother of child said "oh I'm always doing it".
Entertainent - DD has friends of different ages and interests - difficult to find something that will suit a 5 year old and an 11 year old. Or not invite them. Then it becomes my party, my guest list etc. What utter bollocks !!