"We have to leave"

I'm not exactly sure what my children hear when I say that line.
They show absolutely no sense of urgency.  They don't move.  I'm not even sure if they hear me.

"We have to leave now."

There is a little urgency in my voice and still no movement.

"We have to leave......NOW!"

A lot of urgency in my voice.  Little, if any, movement from the kids.

"Get down here.  WE HAVE TO GO NOW!"

We're getting down to the wire and my child(ren) will slowly walk down the stairs.

child:  Did you say something?

Me:  Yes.  We have to leave now.

child:  Why?  Where are we going?  I didn't know we were going anywhere?  Why didn't you tell me we had to go somewhere?

I quickly get in the car.  They slowly follow.

This whole process can take anywhere from 15-30 minutes.  The aggravation level can be quite high (for me) and I wonder why I'm late sometimes when driving them places.

In the car I hear, "why did we have to leave so quickly?

Me:  Because we are supposed to be there five minutes ago.

Child:  Why didn't you tell me sooner?

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