They haven't adapted to online properly.
There's a reason Amazon is popular.
No crowds, fast delivery, first class customer service, often lower prices, subscribe and save and they'll make a charitable donation on your behalf with their Smile program.
So, let's say I need a bag of cat food, a pair of new shorts, 4 pack of beans and new kettle.
I can get those at a department store sure... But would I go to one when I could get them at just Tesco or Asda? Better yet would I bother getting a bus, walking from the stop to the shops, carry everything, worry about people barging me and such...
Or have a nice cuppa and a sit down for 20 minutes and browse Amazon, could have it in my hands tomorrow and a couple quid on its way to a charity.