Radar key for Baby change?

We were out shopping yesterday and I needed to change the baby. This is a small parade of shops with a couple of restaurants so limited number of places I could change him. I popped into McDonald’s as it was the closest and most convenient. However, when I got to the toilet baby change/disabled toilet(there was only one, despite this being quite a large restaurant) was locked and I needed to go and get a radar key to open it. I understand the purpose of radar key on disabled toilets, but it seems really stupid to have one on a baby change facility. Is this normal? It was such a pain in the arse to have to go and get a key from the staff, who were already busy with customers, with a screaming wet baby. I haven’t been out with baby much so haven’t experienced a lot of baby changing facilities.