Agree, knocking in the door is not helpful. The only times I will knock is when I am not sure and need to check if anyone is inside the room.
I am sure the mum inside can hear if there is anyone waiting outside.
Frankly speaking all mums have diaper blow out emergency problem and have to learn to handle it anywhere with limited resources available. However you dislike it, you have to learn to handle it by yourself, in toilet, in car seat, in the car boot. You don\'t need a clean baby room and disturb a mum who is breastfeeding