In DD's case, I think one big factor are also the kids that attend the school. Her school is careful to screen kids - the application process is long, including requiring the parents to sit and watch each primary classroom for 15 minutes - each classroom, despite being the same ages, are very different due to the personalities of the teachers who run the classrooms and the children in the room. So - that tends to filter out disengaged parents or parents who after observation find it is not what they are looking for...
So I suspect that the children that tends to come into her school are more motivated and tend to lean towards being bright as a group.
The other thing I noticed compared to the preschool she was in before (and that DS went to when he was 3), there is a much wider range of "non-academic" activities - those are not ones that people associate with finding GT like pouring water from one container to another, punching a shape with pins which were not present in DS's traditional room, which leaned more towards pretend play/academics.
From what I have seen, because they are so used to having different kids move at different speeds - with most common being that kids will move faster in some areas but not as fast in other areas - teachers are trained to really go with the flow rather than having the whole group doing the same tasks, which is more typical in a traditional room. When the whole group is suppose to be moving together at mostly the same pace, the outliers stand out. When a group disperses to work on their own activities at different levels as the norm, the outliers may not stand out as much, because no one is doing the same activity all together anyway. If a child wants to work on an activity for just 10 minutes, that is fine. If he is engaged for 20-30 minutes, that is usually fine too. They don't have to wait for everyone else if they want to do something else. So I suspect in this environment, teachers are not really pay attention to giftedness.
For 2 year olds, you are going to find that age constraint in many states - teacher/student ratio, naptimes, what the age differentials can be in a group of kids all are set by law that all daycares have to abide by for licensing from what I understood in our state.
Note, what you see at home will not be what teachers see in school. We always joke that we have home DS/DD and school DD/DS - they are always going to be different in different environments. The thing you want to keep an eye on is if she is suppressing who she really is to "fit in" (which we were starting to see in DS as young as 3). But if she is happy and engaged there, I would not worry...
