Sensitivity or specificity? Sensitivity is easy, just say every person is positive and you'll find 100% of true positives. Specificity is the hard problem.
I'm a backend dev. I needed basically a single js function for my personal website that called out to some NPM package. I thought: I'll do this the proper modern way, typescript and everything. Result: under 10 lines of code, but 12 config files (and 1.5h of fiddling with ES Modules vs CommonJS).
The appeal is: 100% of your family and friends use it. A good fraction of businesses use it for customer service too. Not using it will have you left out of a pretty big chunk of social life.
In the Netherlands: whatsapp. You can't avoid whatsapp here. Telegram is used by a smaller fraction, but it got a bit of a bad rep during the pandemic due to primarily attracting anti-vax rioters.
You don't have to feel bad for cutting grass. That's grass its entire evolutionary skitch, albeit naturally with being grazed instead of mechanically cut.
Grass survives cuts extremely well. Most of its mass is below ground. By thriving in areas that are frequently grazed / cut, it outcompetes other plants. Natural meadows without grazers quickly turn into forests. But tree saplings don't survive being eaten, so whenever there are grazers (or human cuts), grass outcompetes trees.
To all the naysayers: if the claims hold up this will be super useful for some industries. Example, I worked at a human genomics lab for diagnostics. By law we were supposed to retain raw data for a whopping 120 years. With a couple terabyte per individual for a WGS, the storage and backup costs were very much non-trivial.
Sensitivity or specificity? Sensitivity is easy, just say every person is positive and you'll find 100% of true positives. Specificity is the hard problem.