This is why, when there is any question of time we take the Carnival tours. If there is plenty of time we'll often book our own (a few months ago in Curacoa we went on a private tour we had booked online because it brought us back to the ship at 1:00 and the ship sailed at 5:00). But otherwise the ship will wait for a Carnival tour to return--this happened to us in Barbados when our tour bus got a flat (naturally no spare!). We got back 45 minutes late, but the ship waited. In Panama there was a HUGE traffic jam, we watched from the balcony as Carnival tour buses arrived about one hour after the ship was scheduled to leave. However, I saw this video, (which someone said was a put on---but I don't agree) showing a "late" couple.
GETTING TO THE SHIP TOO LATE