When a tire is off by 10 PSI and it's not going off warning you ..... that's the problem. I've observed this over the years on Chevy,Kia and Toyota.
They're for people who don't know enough to check their tires.
Sorry don't need them for $200 extra
So how often do you check your tires? Once a day? Once a week? Once a month? The likelihood of someone catching a problem on their own is pretty slim short of an actual complete flat.
My truck shows me the actual PSI of each tire...so even without the warning light coming on I can see if one tire suddenly starts to drop a few PSI to signify a potential issue. Even for cars that don't show the exact PSI, a warning light coming on when it is 10 PSI below the recommended level is still better than not having it at all.