"Has there ever been a case where a small child was taken from their mother, in a busy shop, by a peodophile?"
Disclaimer: I am not ever in a general anxious state about such an occurrence and don't think it common enough to make generalisations about perma-danger, but...
I met a woman who had her dd snatched from under her nose.
She was in a shop which was part of an arcade leading to a train platform.
She had a baby in a buggy and her DS and DD walking alongside, holding on to the buggy as they had been taught.
In the shop her dd made a massive fuss about wanting sweets, she was resolute in saying 'no, no sweets, we are going home for lunch'
Walking to the barriers, she was distracted by the baby and stopped to deal with him. When she turned back her dd was nowhere to be seen.
Full scale alert - the shop she had been in and the station staff all looked and put out the alert.
After a terrifying time, the station staff told her they had found her dd.
A woman who had witnessed the firm 'no sweets' scene in the shop had been on the platform. As a train, not hers, was stopped on the platform she noticed that the child was on the train, with a man, and was eating a huge ice cream.
She leapt on to the train, put her foot in the door, said to the man 'excuse me is that your child?'. The man froze, she grabbed the child's hand and took her off the train...and unfortunately the train left (but they did get him later) because her first thought was to get the child back to her mother.