These are a couple of recent examples, but stuff like this happens frequently.
On monday evening I asked the younger of our two kids to brush their teeth. My wife said no, the older one should brush theirs first.
This morning, it was my turn to do the school run. DW was sitting at her desk working from home. I call the children to come and get in the car. DW says no, it's not time to go yet, you've got two minutes. So as you'd expect, both children go back up to their rooms and I have to go and retrieve them again two minutes later.
I would never dream of overruling her over something so petty as who brushes their teeth first or a two minute difference in what time to leave the house. I instinctively feel like it's one of those things that you Should Not Do, because it effectively teaches the children that instructions from one of their parents can be safely ignored.
Is it unreasonable to think she shouldn't be doing this?