Because it’s not obvious to most customers that a corner’s been cut. Same reason most new construction in the US sucks.

You can safely put a washer and dryer on the upper floor of a house if you add a proper floor drain, but you’re unlikely to see anyone add a floor drain in new construction because buyers aren’t looking for it. Now multiply that by everything a buyer isn’t looking for and you’re talking real money.

You have companies choosing the component that cost 10 cents instead of 15 cents even if the 10 cents component will break 10 times faster than the more expensive one.

You simply cannot put enough activated carbon in a little foam thing that goes in front of a filter to do anything useful.

The real activated carbon filters have 10s of pounds of carbon. The little black foam thing that comes with those 2-in-1 carbon filters is useless.

But it does cost money and so… corners are cut

The clue is in your name