Digital Cell Phone Scanner Why Are Newer Scanners Becoming Digital?

Why are newer scanners becoming digital? - digital cell phone scanner

To my knowledge, I thought the only thing that has been collected, the digital scanner may not have cell phones (also illegal). So what is worth, taken by digital scanner? ... Or digital mobile phones can be collected?

And also, what are all the systems (eg the police) that you pick up, where a trunking scanner required?