The primary evidence is that they're not getting much traffic. That information is available from public sources. Like any shop, if you're not getting people through the door then you're not going to making many sales. That much is simple common sense. To go into it in a bit more detail requires a knowledge of how traffic generally correlates to sales, something which I do know about as that's an important part of my job. Now, obviously, you don't have to accept that I'm telling the truth about my knowledge and experience (although why would I lie?), but if you're certain that I'm wrong then it would be trivially easy for you to come up with figures which show me to be wrong.
I say I'm right because of my experience and knowledge, and because of publicly available information which backs up my claim. Obviously, that's not going to convicen you, because you're certain that you're right no matter what evidence is placed in front of you. But it's not you that I'm trying to convince.
Mark