Image sensors are incredibly cheap, and being able to compress 720 or 1080p video isn't hard either - many smartphones do it this as a matter of course, while managing to do other things in the background.
I am sure a CCTV camera could capture full HD (or even higher, which would probably be good for security purposes - allowing you to zoom in Blade Runner style) and compress it with H.264 or whatever - and storage is also dirt cheap. I won't do the maths, but if you had 32, 64 or 128GB of SSD storage then you'd be capturing a LOT of data before needing to overwrite it.
You wouldn't necessarily need to capture at 30 or 60fps, so cut the frame rate and you'd get even more again. Finally, on a train or bus where I believe cameras can be remotely viewed, the same system could easily downscale on the fly to reduce the necessary bandwidth to transmit HD video content.
Any company with outdated CCTV that can't capture clear images should be forced to replace it, as we've ended up relying on CCTV at the expense of other more expensive options (like more staff) so we need it to work properly.