Why simply every manufacturer not using screen's small part to illuminate and use like an LED notification ? the biggest example of bad piece of design is Nothing phone where they can use the OLED screen area to lit up and act like an LED instead of useless single colour notification light at the back.
I have aodnotify set around my front camera cutout and it works perfectly. No need for extra LED hardware on the front panel, and there are many configurations you can setup (camera circle, outside of display, etc) with that app.
Remember, the thinner our phones get, the more hardware gets taken out and features we lose. Also, OEM's are constantly trying to save $ - and let's be real: building a "perfect" phone hurts long term sales. That's why they take practical things like a swappable battery and expanded storage (sd card) away from us. They could build phones that could last up to 10 years for most of us, but, again: sales. They want us buying new phones every 2 years. It's all about those $$$ bills, not customer satisfaction.