Think about it - when you ask your little one to "say_______" You're just teaching them the art of imitation. So whilst they might imitate you when you say "say sorry" or "say please", that's not teaching them to say those things in the moment when they feel it. It's just creating little parrots who can imitate words in a meaningless way.
Aside from 'please' and 'sorry', we tend to ask our little ones to say words we've heard them say before because we want to hear it again. We're excited they can talk now and we want to hear that success again and again. But making your baby say their words isn't teaching them any new ones. It's also often out of context - they'll be playing with a toy and an adult says "say cat!" and children are left confused. When we say "say", we're doing it for our own pleasure and not for the well being of our little ones.
PLUS it's a lot of pressure. Every time to ask your child to say something it's like a pop quiz - you're taking language OUT of their language bank instead of feeding it in. Children can become shy to avoid 'performing' for their parents and it can make them talk less. Which is not what we want! They might also say 'sorry' or 'please' just to please you but not feel or mean those things.
INSTEAD: Model the word you'd like to hear IN CONTEXT. So say 'a car!' If they're playing with a car and leave it open for them to talk if they want to. Don't push them to say the words that they know, teach them new words instead. I always say "tell a story to get a story" which means instead of asking questions or saying "say_____" just tell your own story. Say your own words and model language and that'll tempt your little one to tell their story without pressure. Don't force your little one to say sorry or please, just model the word in the moment. They'll pick it up in their own time and when they do, they'll mean it.