First of all, if you're going to ask this question, at least post places thats actually somewhat well known. Like what is Bobs? This must be a small enough business that has like MAYBE a few stores but but not large enough for most to still have heard about it.
Secondly, a lot of the time it's because of bad management and couldn't keep up with changes fast enough. Sort of like Blockbusters refused to go digital at first and even refused Netflix's offer 10+ years ago and look at them now.
Thirdly, convenience. Nowadays we can have things ordered to our front door or at least convenient enough to have it deliver at our closest post office that we can just walk (or short drive) over to pick it up.
Lastly, kind of an add on to the 2nd one, but a lot of the times, it could be because the store's prices and the quality you're paying for might have something to do with it as a lot of the times, it might not make sense in a few factors. Like if you can buy something that's in a similar quality but for much cheaper and or more convenient, most would go with that route as oppose to go out of your way to get something that's more expensive but has similar quality.