Why don’t banks use security cameras with higher resolution?

Hello guys, I’m currently working on a consulting project.
My client is a bank and they want to do video analytics on their customers. Let’s not talk about the details here…
Here’s the question: I’ve checked the image from their security cameras and the video quality is extremely low.
This makes me wonder… why do the cameras have such a low quality? I think they can afford good ones?
Or is there any specific reasons? Does anyone have idea on this?