Spot on Tim. The League Cup final both teams always get 32,000 plus allocations making it easier for supporters to get a ticket most of the time. Also the League Cup for the past few years has always been a 4pm/4.30pm kick off time and that is not going to change as it allows Sky to show a 1.30pm/2pm kick off beforehand without any concerns. They wouldn't want League Cup earlier again in case of extra time and penalties overrunning into their next live tv game - rightly or wrongly that is the way it is.
FA Cup final is slightly different as it is about 25,000 and so for any non-season ticket holders there is a bit more jeopardy in whether you will get a ticket. I.e. v Stoke and Wigan sold out in a couple of days whereas the final v Watford took a few days longer.