New pre-hung door question

I just had a new prehung door installed. The shape and design of the jam is slightly different than the original. I noticed the installer installed the new door with the bottom of the jam on the existing floor and did not cut the flooring to have the jam reach the subfloor. Now the flooring around the new jam has gaps and the trim around the door is higher than my other doors in the hallway. Is this incorrect? Shouldn't the bottom of the jam be trimmed at a minimum so the door trims all match? Thank you