Background designer: Detecting real life objects properly and removing their background

I've tried multiple times to use the Ai background designer, but unfortunately it doesn't work properly on real life pictures. I wanted to remove the background of a picture which has an antique phone in it, but the system doesn't detect the phone properly.:( I would be a big help if you could advance this feature so that it can properly detect real life objects. I atteched one of the failed attempts.