there's a big difference between a mum who is at the park and on the phone as her kids are running around having fun, and putting it down as they come and ask for something, and a mum who is on her phone, whilst the child is next to her, desperately trying to engage her in conversation, and the child is completely ignored for her phone and then told to bugger off, sadly even heard 'p* off'.
I was last year on the train back home, 2 hours journey. 4 seats facing. A mum was there with her boy who looked about 5, whose was on his first train journey. For more than 1/2 hour, he kept saying 'mum, mum, mum, look there's a horse, look mum, there's a tractor, mum, where do you think the other train is going. Mum, why did we stop'. He was adorable, so excited, so engrossed, and so wanted to communicate with his mum and not once, not once did she look up from her phone and respond to him. After all this time, I felt so sorry for him, I started to talk to him. His excited and eager response did made me wonder how often it happened. After we exchanged a few words, she looked me up, gave me a dirty look and got another phone and told him to play a game.
I really don't think it's an exception. Some parents can't be bothered to engage and that's that. It's one of the key reasons why kids gets free childcare at 3, and some at 2.