Also gives particularly a shy kid that takes time to become comfortable a chance to come out of their shell a bit and interact.

I thought the same thing but it goes by very quickly. Don't worry.

Ours is an hour. There's some group play and then some one-on-one with an educator/evaluator, so they need to allow some time for each segment.

It is not that long, really. If your child cannot pay attention and be a good child for 1.5 hours, they may not be ready for school just yet. Where are you applying that your child is 3 years old for the play date?!?

Dd has two play date interviews lined up so far, and they are both about 1.5 hours. That's a long time to ask a 3-yr old to be "on" in a room full of strangers. Is this length of time new? I thought they used to be 45 min.