Yup...and the 'special' family line for Side B is all the way over to the right! I have also been looked at, with my dd, and directed to that line. Nope, I politely responded. We are heading to the black diamond 'experienced' fliers line. The TSA person tried to tell me that since we were a 'family' we needed to go in that line. I explained that my dd has more air miles under her belt than a lot of the 'adults only' in the black diamond line. He watched us as we proceeded through the line. I think that even he was taken aback at my dd's ability to not hold up those behind us. Wish I could have said the same about those in front of us.
True, I've seen some families with kids move alot quicker through the experienced flyers' line than some adults, but I've also seen the opposite too. Last Oct I got stuck behind a totally clueless family in that line. The TSA agent saw them and directed them over to the family line. They refused, saying they had flown before and were experienced flyers.

None of them knew what they were doing. They were talking and fussing about how the TSA agent had insulted them by thinking they didn't know what to do. They were so busy complaining about the TSA agent asking them to switch lines, that they were not paying attention to what everyone else was doing. They had to be told to take their shoes off. The mom said, "We didn't the last time we flew and they're just flip flops anyway".

She then set the alarm off with all her jewelery and hair doo dads. Dad set the alarm off with his belt buckle and then set it off again with all the change in his pocket. Their carry ons set it off with a small snow globe in a kid's carry on, a laptop in the dad's that they hadn't taken out, and some lotion in the mom's.

Yeah, they were really experienced travelers.


They were so busy talking about how experienced they were, that they couldn't bother to even listen to the TSA agents yelling out basic instructions to everyone.
Returning to the original question (play nicely people) I'm sure that some people have missed their flight home because of security lines. But that was more likely the result of poor planning on their part.
It's not always poor planning on someone's part. I was getting on a DME bus once (when I was supposed to--about 3 hours prior to my flight), when some family came running up demanding to be put on our bus. They had missed their DME bus and insisted on being accommodated on ours. The bus driver explained that after his next stop, the the bus would be full, so they wouldn't fit. The dad kept insisting. Both the driver and the CM that stands there with a clip board kept telling him there wasn't room and they should not have missed their bus. The dad finally admitted they thought it was ridiculous for the DME bus pickups to be three hours prior to your flight and had intentionally missed their bus, planning to get on the next one. However, they got tied up longer then they'd planned at DTD, then the bus service from DTD back to the resort was slow, so they were later than they planned and were now in danger of missing their flight. They demanded that since their flight was leaving soon and we had more time, that some of us be kicked off, to accommodate them.

The driver and CM both said that wasn't happening. The dad then jumped on the bus and told his family to come on and they'd just stand then. When told that wasn't allowed, he refused to get off, demanding that Disney get him to the airport immediately. A manager was called who finally talked him off the bus, but by that time we were running late and still had another stop to make. Then to make matters worse on the way to the airport we got caught in a traffic jam, due to a big wreck. Then when we finally got to the airport we were the second stop. By the time I got through security, caught the tram and rushed to my gate they were starting to board. I caught the flight, but was late, due to no fault of my own.