Waste of what

The article itself mentions how it is a loophole in the privacy laws

They don’t use it as admissible evidence, they use it to find out whether someone is worth pursuing in legitimate ways that are more time and effort intensive.

Zero day backdoors without any interaction from the user are proven possible. Look at Pegasus spyware. The majority of data breaches are due to zero day hacks.

Buying what? Like you don’t believe the police can, will, or has done this?