NJ, I also don't understand why adults believe the world is entirely for them... and wish to believe children and babies don't exist/ don't need familiarisation or education in different circumstances.
Occasionally, yes, it may be more appropriate for adults-only, from the child's point of view. But not in general. Believe it or not, parents never like to see or hear their child distressed either, and would do everything they can to solve it. Including leaving early if necessary. The parents will not enjoy it with a "wailing baby,".