Really School doesn't let child wait in office

So im having my mom pick up my oldest. My tires on my car need to be replaced. Found that out today when I had little to no traction. Its been raining hard all day. So I really didnt want to risk it with my girls. Pepole seem to turn stupid when it rains. If I do anying under the speed limit I have askholes on my ass. God forbid I do 5 under due to shatty weather. Okay back to my post. This is the first time my mom is going to her school. Just started a new one this year. I asked the office to have my oldest wait in the office just this once because my mom isnt familiar with the school. She gave me a ton of attitude and kept saying we dont normally do that. I asked her nicely again and she said okay. I just didnt get it. Sometimes my daughter is out by all the kids other times the teacher holds them back till they all line up right.Ive had to wait longer then 5 min after the bell most days. Its pooring rain and I just Didn't want my mom not knowing where to go... I just don't get why she couldn't wait in the office. I mean i got them to say yes but that was after asking a couple times and trying to explain the situation. Also i tried to explain where to go to my mom. Love her to death but shes a air head some days. Anyone have this rule at there school. This is a first for me.