I used to work for B&Q and the main reason why some plants are put in the casualty bay is the lack of staff to do the watering. My store only had 2 people to look after the gardening dept including all the mowers etc. If one went on holiday, management never got someone else to help, therefore the watering was way down on the list. Big companies like this will still make a profit even selling at knockdown prices because they are able to buy in bulk. The margins tend to be very high.