Find me Logic here

This is from Friday Flash - the school circular from my daughters school:
Morning Car Rider Reminder:
You are welcome to bring your child as a car rider or send them on the bus, but they still must be here, in the building, by 8:50 in order to be counted present and on time. Beingvin line at 8:50 (even if you have been in line for several minutes) does not mean your child is on time.

We will post the yellow sign as soon as the bell rings. Once you see the sign, you will need to drive around to the front to check in your child since they are tardy. You can not do this until 8:50.

We understand this is frustrating....

You may drop off your child beginning at 8:20.

Under no circumstances should students be dropped off in front of the school - even if the car rider line is backed up.

So basically what it mean...
You are car rider - you can use that 30 minute window to drop your child - if there is long backed up line, still you can not drop your child in front of the school before 8:50 - and you stuck in line and your number don't come till 8:50 - your child should get tardy slip

find me logic here please.....