my grandfather cant even hear the beeping, let alone if the microwave is running.

And increasing beeping volume would be good. First beep should be nearly muted. 4th beep should be judging.

Also hum of a microwave is fairly easy to tune out.

Mine doesn't have any kind of mute option, I checked the manual.

My ADHD brain can barely remember putting something in the microwave. I need the beep to remind myself to check it

It’s probably way cheaper to add a speaker than an actual, physical bell. But I agree. My microwave dings and I’m fine with that.