Ludwig - // There are people who believe babies should be left to cry without being attended to, basically until they shut up, however long that takes, and that this is in some way good for them. This couple could be a pair of these weirdos for all we know. //
I think Ludwig raises a valid point here.
Babies cry for a reason - all you have to do is find out the reason, address it, and the crying stops.
Fortunately, babies are not complex creatures, so a few simple explorations will usually find the reason for baby's distress -
hungry / thirsty / dirty / pain with wind / over-tired / hot / cold / bored / lost dummy / feels like a cuddle ..
and you can explore all those situations in about one and a half minutes, and address them in two minutes, and baby will stop crying.
There is the old wives' tale that a baby is 'exercising her lungs ...' which is obviously bonkers.
Babies communicate every wish and need by crying - learn to recognise your baby's different cries, and sort out what they need, and they either go to sleep, or remain awake and contented.
It's just parenthood - if people don't do it instinctively, they need to learn.