Because of two reasons together: charcoal filters don’t remove bacteria[1][2], that is the reason why I don’t expect it to reduce bacterial count. And then any user error (less than pristine pitcher, filter not replaced at the recomended interval) would increase the count.
But there is also a different reasoning. A more philosophical, heuristic based one: The water where I live is treated by professionals with professional grade equipment. They also take regular samples and try to grow the bacteria to be able to tell if they are doing their job right or not. And the quality, at least where I live, is generally good. To improve something from good to excelent you often need to put in as much work as it was already put in to move it from mediocre to good. It is possible of course, but I would expect the process to be either energy intensive, or fiddly, or resource intensive, or require even more specialised equipment. Most likely all four at once. A simple, easy to use, and convenient filter doesn’t pass my sniff test. Like if it is that easy why wouldn’t the pros just do it at the water treatment facility?
Now of course this is just a heuristic, it can go wrong many different ways. And I admit I can be wrong of course. This is very far from my expertise. But this is how I was thinking about the question.
But there is also a different reasoning. A more philosophical, heuristic based one: The water where I live is treated by professionals with professional grade equipment. They also take regular samples and try to grow the bacteria to be able to tell if they are doing their job right or not. And the quality, at least where I live, is generally good. To improve something from good to excelent you often need to put in as much work as it was already put in to move it from mediocre to good. It is possible of course, but I would expect the process to be either energy intensive, or fiddly, or resource intensive, or require even more specialised equipment. Most likely all four at once. A simple, easy to use, and convenient filter doesn’t pass my sniff test. Like if it is that easy why wouldn’t the pros just do it at the water treatment facility?
Now of course this is just a heuristic, it can go wrong many different ways. And I admit I can be wrong of course. This is very far from my expertise. But this is how I was thinking about the question.
1: https://www.livestrong.com/article/193977-what-do-carbon-fil...
2: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC242697/