The use of "CCTV", or more current, "video surveillance", is not only about attempting to gain a direct view of a perp's face (which we know is not always successful), it also is for gathering data on overall physical appearance, gait, height, physical mannerisms and environmental and situational interactions.
At least some "VHS" or similar tape-based systems remain in use but I have no statistics. Current digital camera technology far surpasses VHS/Beta in video quality and usable coverage. But not all digital cameras offer those improvements, especially older, first and second generation devices. Current resolution (total pixels, i.e., 2, 4, 5, 8, 10, 12+ MP) has increased dramatically but many older digital devices remain in place and are 'functional' and owners are reluctant to replace something that "works".
Higher resolution (5+ MP) provide more detail, which enables better zoom quality: the more detail contained within an image the better the zoom quality.
Lens choice, camera placement and aim also are critical factors to consider. Some cameras come with a fixed lens (not interchangeable), more expensive cameras offer a choice of lenses, such as narrow-angle or wide-angle, power zoom, etc. Some cameras also include pan/tilt/zoom capability in a consolidated unit while other cameras without those features may be mounted on pan/tilt mechanisms to achieve the same coverage and if the camera accepts interchangeable lenses a zoom model might be available.
If LE releases surveillance video and it appears 'blurry' it is usually a result of zooming of a lower-resolution image. Zooming the image recorded from higher resolution cameras provides a less 'blurry' result, with the highest pixel models providing excellent clarity.
The lowest resolution digital camera you purchase should be at least 2 MP (1920 x 1080) but I prefer 8+ MP (3840 x 2160 and better) for best quality and coverage capability. Prices are coming down (little by little and only to a point since 'technology pricing' tends to linger with certain devices), and recording devices and software currently available provide more features that meet and exceed most user's needs. You may use a computer or dedicated device, either of which must be powered on and functional 24/7/365 for true, total surveillance.