For your child's safety purposes

I was in a local supermarket when I spotted this notice. It reads "For your child's safety purposes, avoid placing them on the trolley."

There are two obvious mistakes in the notice. First, the word 'purposes' need not be there. Secondly, the word 'child' is singular, but "them" after 'placing' does not agree with 'child' which is singular.

It will sound better if the notice is worded as "For your child's safety, do not place him or her on the trolley."